Mk/Uses/php.mk: fix build of all PHP modules when using php74 on GCC architectures

[pkubaj]

Summary

php74 introduced C11 requirement and all optional PHP modules available in the ports tree need a patch like this:

.include <bsd.port.options.mk>
.if ${FLAVOR} == php74
USES+=compiler:c11
.endif

Better keep it in Mk to make it easier.

PR: 240883