When building with apxs from Apache 1.3.6, I get regex errors. This occurs whether or not I use the --with-system-regex configure option. PHP will compile file if I just use --with-shared-apache.  I'm using the following configure options:

./configure --with-apxs\
            --with-mysql\
            --enable-debug=no --enable-track-vars=yes

From that I received the following output:

parser.tab.o
In file included from /usr/include/apache/ap_config.h:1011,
                 from php.h:191,
                 from language-parser.y:57:
/usr/include/apache/hsregex.h:41: warning: `REG_EXTENDED' redefined
/usr/include/regex.h:252: warning: this is the location of the previous definition
/usr/include/apache/hsregex.h:42: warning: `REG_ICASE' redefined
/usr/include/regex.h:256: warning: this is the location of the previous definition
/usr/include/apache/hsregex.h:43: warning: `REG_NOSUB' redefined
/usr/include/regex.h:265: warning: this is the location of the previous definition
/usr/include/apache/hsregex.h:44: warning: `REG_NEWLINE' redefined
/usr/include/regex.h:261: warning: this is the location of the previous definition
/usr/include/apache/hsregex.h:74: warning: `REG_NOTBOL' redefined
/usr/include/regex.h:275: warning: this is the location of the previous definition
/usr/include/apache/hsregex.h:75: warning: `REG_NOTEOL' redefined
/usr/include/regex.h:278: warning: this is the location of the previous definition
In file included from /usr/include/apache/ap_config.h:1011,
                 from php.h:191,
                 from language-parser.y:57:
/usr/include/apache/hsregex.h:25: conflicting types for `regoff_t'
/usr/include/regex.h:390: previous declaration of `regoff_t'
/usr/include/apache/hsregex.h:31: conflicting types for `regex_t'
/usr/include/regex.h:387: previous declaration of `regex_t'
/usr/include/apache/hsregex.h:35: conflicting types for `regmatch_t'
/usr/include/regex.h:418: previous declaration of `regmatch_t'
/usr/include/apache/hsregex.h:39: conflicting types for `regcomp'
/usr/include/regex.h:513: previous declaration of `regcomp'
/usr/include/apache/hsregex.h:69: conflicting types for `regerror'
/usr/include/regex.h:519: previous declaration of `regerror'
/usr/include/apache/hsregex.h:73: conflicting types for `regexec'
/usr/include/regex.h:516: previous declaration of `regexec'
/usr/include/apache/hsregex.h:83: conflicting types for `regfree'
/usr/include/regex.h:520: previous declaration of `regfree'
make: *** [language-parser.tab.o] Error 1