Cannot compile as DSO using compile option --with-apxs2 (full compile options are as follows)

./configure --enable-sockets --with-apxs2=/opt/apache2/bin/apxs --without-mysql --with-oci8=/opt/product/oracle/8.1.6 --with-pspell --with-dom --prefix=/opt/php

Error when running make:

In file included from sapi_apache2.c:33:
/opt/apache2/include/util_filter.h:153: parse error before `ap_bucket_brigade'
/opt/apache2/include/util_filter.h:154: parse error before `ap_bucket_brigade'
/opt/apache2/include/util_filter.h:285: parse error before `ap_bucket_brigade'
/opt/apache2/include/util_filter.h:297: parse error before `ap_bucket_brigade'
/opt/apache2/include/util_filter.h:404: parse error before `ap_bucket_brigade'
In file included from sapi_apache2.c:35:
/opt/apache2/include/http_config.h:965: parse error before `int'
In file included from sapi_apache2.c:44:
php_apache.h:24: parse error before `ap_bucket_brigade'
php_apache.h:24: warning: no semicolon at end of struct or union
php_apache.h:32: parse error before `}'
php_apache.h:32: warning: data definition has no type or storage class
sapi_apache2.c: In function `php_apache_sapi_ub_write':
sapi_apache2.c:49: `ap_bucket' undeclared (first use in this function)
sapi_apache2.c:49: (Each undeclared identifier is reported only once
sapi_apache2.c:49: for each function it appears in.)
sapi_apache2.c:49: `b' undeclared (first use in this function)
sapi_apache2.c:50: `ap_bucket_brigade' undeclared (first use in this function)
sapi_apache2.c:50: `bb' undeclared (first use in this function)
sapi_apache2.c:51: `ctx' undeclared (first use in this function)
sapi_apache2.c:52: parse error before `now'
sapi_apache2.c:55: `sapi_globals' undeclared (first use in this function)
sapi_apache2.c:61: `now' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_header_handler':
sapi_apache2.c:77: `ctx' undeclared (first use in this function)
sapi_apache2.c:78: parse error before `char'
sapi_apache2.c:80: `val' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_send_headers':
sapi_apache2.c:105: `ctx' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_read_post':
sapi_apache2.c:117: `ctx' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_read_cookies':
sapi_apache2.c:136: `ctx' undeclared (first use in this function)
sapi_apache2.c:137: parse error before `const'
sapi_apache2.c:139: `http_cookie' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_register_variables':
sapi_apache2.c:148: `ctx' undeclared (first use in this function)
sapi_apache2.c:149: parse error before `*'
sapi_apache2.c:152: `arr' undeclared (first use in this function)
sapi_apache2.c:152: `key' undeclared (first use in this function)
sapi_apache2.c:152: `val' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_flush':
sapi_apache2.c:163: `ctx' undeclared (first use in this function)
sapi_apache2.c:164: `ap_bucket_brigade' undeclared (first use in this function)
sapi_apache2.c:164: `bb' undeclared (first use in this function)
sapi_apache2.c:165: `ap_bucket' undeclared (first use in this function)
sapi_apache2.c:165: `b' undeclared (first use in this function)
sapi_apache2.c: In function `php_apache_sapi_log_message':
sapi_apache2.c:182: `ctx' undeclared (first use in this function)
sapi_apache2.c:183: parse error before `*'
sapi_apache2.c:185: `sapi_globals' undeclared (first use in this function)
sapi_apache2.c: At top level:
sapi_apache2.c:233: parse error before `ap_bucket_brigade'
sapi_apache2.c: In function `php_input_filter':
sapi_apache2.c:236: `ctx' undeclared (first use in this function)
sapi_apache2.c:237: parse error before `long'
sapi_apache2.c:238: `ap_bucket' undeclared (first use in this function)
sapi_apache2.c:238: `b' undeclared (first use in this function)
sapi_apache2.c:239: parse error before `const'
sapi_apache2.c:244: `sapi_globals' undeclared (first use in this function)
sapi_apache2.c:248: `rv' undeclared (first use in this function)
sapi_apache2.c:248: `bb' undeclared (first use in this function)
sapi_apache2.c:248: `mode' undeclared (first use in this function)
sapi_apache2.c:252: parse error before `{'
sapi_apache2.c:254: `n' undeclared (first use in this function)
sapi_apache2.c:255: `old_index' undeclared (first use in this function)
sapi_apache2.c:258: `str' undeclared (first use in this function)
sapi_apache2.c: At top level:
sapi_apache2.c:261: parse error before `return'
sapi_apache2.c:264: parse error before `php_struct'
sapi_apache2.c: In function `php_apache_request_ctor':
sapi_apache2.c:273: `sapi_globals' undeclared (first use in this function)
sapi_apache2.c:283: `ctx' undeclared (first use in this function)
sapi_apache2.c: At top level:
sapi_apache2.c:307: parse error before `ap_bucket_brigade'
sapi_apache2.c: In function `php_output_filter':
sapi_apache2.c:309: `ctx' undeclared (first use in this function)
sapi_apache2.c:310: `ap_bucket' undeclared (first use in this function)
sapi_apache2.c:310: `b' undeclared (first use in this function)
sapi_apache2.c:311: parse error before `rv'
sapi_apache2.c:317: `sapi_globals' undeclared (first use in this function)
sapi_apache2.c:329: `conf' undeclared (first use in this function)
sapi_apache2.c:337: `bb' undeclared (first use in this function)
sapi_apache2.c:346: `eos' undeclared (first use in this function)
sapi_apache2.c:347: parse error before `*'
sapi_apache2.c:359: `core_globals' undeclared (first use in this function)
sapi_apache2.c:363: parse error before `{'
sapi_apache2.c:365: `rv' undeclared (first use in this function)
sapi_apache2.c:365: `n' undeclared (first use in this function)
sapi_apache2.c:366: `str' undeclared (first use in this function)
sapi_apache2.c:370: `content' undeclared (first use in this function)
sapi_apache2.c:382: `fd' undeclared (first use in this function)
sapi_apache2.c:388: `zfd' undeclared (first use in this function)
sapi_apache2.c:393: `compiler_globals' undeclared (first use in this function)
sapi_apache2.c:393: `executor_globals' undeclared (first use in this function)
sapi_apache2.c: At top level:
sapi_apache2.c:414: parse error before `else'
sapi_apache2.c: In function `php_register_hook':
sapi_apache2.c:441: `AP_HOOK_MIDDLE' undeclared (first use in this function)
sapi_apache2.c: At top level:
sapi_apache2.c:454: warning: initialization from incompatible pointer type
make[3]: *** [sapi_apache2.lo] Error 1