Description:
------------
After working around Bug #70991
[I modified ext/opcache/zend_file_cache.c to always include sys/uio.h ... otherwise the compilation stops there already.]

The next one is when linking

ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0xff9): In function `pcre_jit_free_unused_memory':
/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:117: undefined reference to `pthread_mutex_lock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x3e7c): In function `sljit_free_code':
/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:117: undefined reference to `pthread_mutex_lock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x4834): In function `sljit_generate_code':
/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:117: undefined reference to `pthread_mutex_lock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x48ab):/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:122: undefined reference to `pthread_mutex_unlock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x4a23):/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:122: undefined reference to `pthread_mutex_unlock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x4d0b):/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:122: undefined reference to `pthread_mutex_unlock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x106e): In function `pcre_jit_free_unused_memory':
/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:122: undefined reference to `pthread_mutex_unlock'
ext/pcre/pcrelib/.libs/pcre_jit_compile.o(.text+0x3f00): In function `sljit_free_code':
/<PATH>/php-7.0.0/ext/pcre/pcrelib/sljit/sljitUtils.c:122: undefined reference to `pthread_mutex_unlock'
collect2: ld returned 1 exit status
*** Error code 1

AFAIK this "monster" command:
/bin/sh /usr/src/3rdparty/php-7.0.0/libtool --silent --preserve-dup-deps --mode=link cc -export-dynamic -I/usr/local/include -g -O2 -fvisibility=hidden   -L/usr/local/lib  -R /usr/local/lib ext/date/php_date.lo ext/date/lib/astro.lo ext/date/lib/dow.lo ext/date/lib/parse_date.lo ext/date/lib/parse_tz.lo ext/date/lib/timelib.lo ext/date/lib/tm2unixtime.lo ext/date/lib/unixtime2tm.lo ext/date/lib/parse_iso_intervals.lo ext/date/lib/interval.lo ext/libxml/libxml.lo ext/pcre/pcrelib/pcre_chartables.lo ext/pcre/pcrelib/pcre_ucd.lo ext/pcre/pcrelib/pcre_compile.lo ext/pcre/pcrelib/pcre_config.lo ext/pcre/pcrelib/pcre_exec.lo ext/pcre/pcrelib/pcre_fullinfo.lo ext/pcre/pcrelib/pcre_get.lo ext/pcre/pcrelib/pcre_globals.lo ext/pcre/pcrelib/pcre_maketables.lo ext/pcre/pcrelib/pcre_newline.lo ext/pcre/pcrelib/pcre_ord2utf8.lo ext/pcre/pcrelib/pcre_refcount.lo ext/pcre/pcrelib/pcre_study.lo ext/pcre/pcrelib/pcre_tables.lo ext/pcre/pcrelib/pcre_valid_utf8.lo ext/pcre/pcrelib/pcre_version.lo ext/pcre/pcrelib/pcre_xclass.lo ext/pcre/pcrelib/pcre_jit_compile.lo ext/pcre/php_pcre.lo ext/sqlite3/sqlite3.lo ext/sqlite3/libsqlite/sqlite3.lo ext/ctype/ctype.lo ext/dom/php_dom.lo ext/dom/attr.lo ext/dom/document.lo ext/dom/domerrorhandler.lo ext/dom/domstringlist.lo ext/dom/domexception.lo ext/dom/namelist.lo ext/dom/processinginstruction.lo ext/dom/cdatasection.lo ext/dom/documentfragment.lo ext/dom/domimplementation.lo ext/dom/element.lo ext/dom/node.lo ext/dom/string_extend.lo ext/dom/characterdata.lo ext/dom/documenttype.lo ext/dom/domimplementationlist.lo ext/dom/entity.lo ext/dom/nodelist.lo ext/dom/text.lo ext/dom/comment.lo ext/dom/domconfiguration.lo ext/dom/domimplementationsource.lo ext/dom/entityreference.lo ext/dom/notation.lo ext/dom/xpath.lo ext/dom/dom_iterators.lo ext/dom/typeinfo.lo ext/dom/domerror.lo ext/dom/domlocator.lo ext/dom/namednodemap.lo ext/dom/userdatahandler.lo ext/fileinfo/fileinfo.lo ext/fileinfo/libmagic/apprentice.lo ext/fileinfo/libmagic/apptype.lo ext/fileinfo/libmagic/ascmagic.lo ext/fileinfo/libmagic/cdf.lo ext/fileinfo/libmagic/cdf_time.lo ext/fileinfo/libmagic/compress.lo ext/fileinfo/libmagic/encoding.lo ext/fileinfo/libmagic/fsmagic.lo ext/fileinfo/libmagic/funcs.lo ext/fileinfo/libmagic/is_tar.lo ext/fileinfo/libmagic/magic.lo ext/fileinfo/libmagic/print.lo ext/fileinfo/libmagic/readcdf.lo ext/fileinfo/libmagic/softmagic.lo ext/filter/filter.lo ext/filter/sanitizing_filters.lo ext/filter/logical_filters.lo ext/filter/callback_filter.lo ext/hash/hash.lo ext/hash/hash_md.lo ext/hash/hash_sha.lo ext/hash/hash_ripemd.lo ext/hash/hash_haval.lo ext/hash/hash_tiger.lo ext/hash/hash_gost.lo ext/hash/hash_snefru.lo ext/hash/hash_whirlpool.lo ext/hash/hash_adler32.lo ext/hash/hash_crc32.lo ext/hash/hash_fnv.lo ext/hash/hash_joaat.lo ext/iconv/iconv.lo ext/json/json.lo ext/json/json_encoder.lo ext/json/json_parser.lo ext/json/json_scanner.lo ext/pdo/pdo.lo ext/pdo/pdo_dbh.lo ext/pdo/pdo_stmt.lo ext/pdo/pdo_sql_parser.lo ext/pdo/pdo_sqlstate.lo ext/pdo_sqlite/pdo_sqlite.lo ext/pdo_sqlite/sqlite_driver.lo ext/pdo_sqlite/sqlite_statement.lo ext/phar/util.lo ext/phar/tar.lo ext/phar/zip.lo ext/phar/stream.lo ext/phar/func_interceptors.lo ext/phar/dirstream.lo ext/phar/phar.lo ext/phar/phar_object.lo ext/phar/phar_path_check.lo ext/posix/posix.lo ext/reflection/php_reflection.lo ext/session/mod_user_class.lo ext/session/session.lo ext/session/mod_files.lo ext/session/mod_mm.lo ext/session/mod_user.lo ext/simplexml/simplexml.lo ext/simplexml/sxe.lo ext/spl/php_spl.lo ext/spl/spl_functions.lo ext/spl/spl_engine.lo ext/spl/spl_iterators.lo ext/spl/spl_array.lo ext/spl/spl_directory.lo ext/spl/spl_exceptions.lo ext/spl/spl_observer.lo ext/spl/spl_dllist.lo ext/spl/spl_heap.lo ext/spl/spl_fixedarray.lo ext/standard/crypt_freesec.lo ext/standard/crypt_blowfish.lo ext/standard/crypt_sha512.lo ext/standard/crypt_sha256.lo ext/standard/php_crypt_r.lo ext/standard/array.lo ext/standard/base64.lo ext/standard/basic_functions.lo ext/standard/browscap.lo ext/standard/crc32.lo ext/standard/crypt.lo ext/standard/cyr_convert.lo ext/standard/datetime.lo ext/standard/dir.lo ext/standard/dl.lo ext/standard/dns.lo ext/standard/exec.lo ext/standard/file.lo ext/standard/filestat.lo ext/standard/flock_compat.lo ext/standard/formatted_print.lo ext/standard/fsock.lo ext/standard/head.lo ext/standard/html.lo ext/standard/image.lo ext/standard/info.lo ext/standard/iptc.lo ext/standard/lcg.lo ext/standard/link.lo ext/standard/mail.lo ext/standard/math.lo ext/standard/md5.lo ext/standard/metaphone.lo ext/standard/microtime.lo ext/standard/pack.lo ext/standard/pageinfo.lo ext/standard/quot_print.lo ext/standard/rand.lo ext/standard/soundex.lo ext/standard/string.lo ext/standard/scanf.lo ext/standard/syslog.lo ext/standard/type.lo ext/standard/uniqid.lo ext/standard/url.lo ext/standard/var.lo ext/standard/versioning.lo ext/standard/assert.lo ext/standard/strnatcmp.lo ext/standard/levenshtein.lo ext/standard/incomplete_class.lo ext/standard/url_scanner_ex.lo ext/standard/ftp_fopen_wrapper.lo ext/standard/http_fopen_wrapper.lo ext/standard/php_fopen_wrapper.lo ext/standard/credits.lo ext/standard/css.lo ext/standard/var_unserializer.lo ext/standard/ftok.lo ext/standard/sha1.lo ext/standard/user_filters.lo ext/standard/uuencode.lo ext/standard/filters.lo ext/standard/proc_open.lo ext/standard/streamsfuncs.lo ext/standard/http.lo ext/standard/password.lo ext/standard/random.lo ext/tokenizer/tokenizer.lo ext/tokenizer/tokenizer_data.lo ext/xml/xml.lo ext/xml/compat.lo ext/xmlreader/php_xmlreader.lo ext/xmlwriter/php_xmlwriter.lo TSRM/TSRM.lo TSRM/tsrm_strtok_r.lo main/main.lo main/snprintf.lo main/spprintf.lo main/php_sprintf.lo main/fopen_wrappers.lo main/alloca.lo main/php_scandir.lo main/php_ini.lo main/SAPI.lo main/rfc1867.lo main/php_content_types.lo main/strlcpy.lo main/strlcat.lo main/mergesort.lo main/reentrancy.lo main/php_variables.lo main/php_ticks.lo main/network.lo main/php_open_temporary_file.lo main/output.lo main/getopt.lo main/streams/streams.lo main/streams/cast.lo main/streams/memory.lo main/streams/filter.lo main/streams/plain_wrapper.lo main/streams/userspace.lo main/streams/transports.lo main/streams/xp_socket.lo main/streams/mmap.lo main/streams/glob_wrapper.lo Zend/zend_language_parser.lo Zend/zend_language_scanner.lo Zend/zend_ini_parser.lo Zend/zend_ini_scanner.lo Zend/zend_alloc.lo Zend/zend_compile.lo Zend/zend_constants.lo Zend/zend_dtrace.lo Zend/zend_execute_API.lo Zend/zend_highlight.lo Zend/zend_llist.lo Zend/zend_vm_opcodes.lo Zend/zend_opcode.lo Zend/zend_operators.lo Zend/zend_ptr_stack.lo Zend/zend_stack.lo Zend/zend_variables.lo Zend/zend.lo Zend/zend_API.lo Zend/zend_extensions.lo Zend/zend_hash.lo Zend/zend_list.lo Zend/zend_builtin_functions.lo Zend/zend_sprintf.lo Zend/zend_ini.lo Zend/zend_sort.lo Zend/zend_multibyte.lo Zend/zend_ts_hash.lo Zend/zend_stream.lo Zend/zend_iterators.lo Zend/zend_interfaces.lo Zend/zend_exceptions.lo Zend/zend_strtod.lo Zend/zend_gc.lo Zend/zend_closures.lo Zend/zend_float.lo Zend/zend_string.lo Zend/zend_signal.lo Zend/zend_generators.lo Zend/zend_virtual_cwd.lo Zend/zend_ast.lo Zend/zend_objects.lo Zend/zend_object_handlers.lo Zend/zend_objects_API.lo Zend/zend_default_classes.lo Zend/zend_inheritance.lo Zend/zend_smart_str.lo Zend/zend_execute.lo main/internal_functions_cli.lo sapi/cli/php_cli.lo sapi/cli/php_http_parser.lo sapi/cli/php_cli_server.lo sapi/cli/ps_title.lo sapi/cli/php_cli_process_title.lo -liconv -liconv -lm -lxml2 -lz -liconv -lm -lxml2 -lz -liconv -lm -lxml2 -lz -liconv -lm -lxml2 -lz -liconv -lm -lxml2 -lz -liconv -lm -lxml2 -lz -liconv -lm  -o sapi/cli/php
needs an -lpthread in there as well on OpenBSD ... 
[I'm not familiar with the build system itself]
If I add it manually I can go beyond to where phpdbg and again php-cgi is linked ... (same problem there)