lang/php81: Runtime fix

• php modules while build with system pcre fails to run when using apache httpd and mod_php. So OPTIONIZE and add as a non-DEFAULT option. However to my knowledge and experience I haven't faced this with nginx and php-fpm yet. [1]
• There is another corner case with apache httpd and mod_php when run on 13.2-RELEASE or newer specially on versions where ASLR is by default turned on. All modules specialy opcache crashes httpd. So add a warning message to advise users to move into php-fpm. [2]

Thanks to brnrd@ for the patch. [2]

PR: 275522 [1], 268318 [2]
Reported by: majo-bugs.freebsd.org@cerny.sk [1], zarychtam@plan-b.pwste.edu.pl [2]