When updating php, I got the following message: * The module you are trying to install (php) * will only work with one of the following MPMs: * event leader metuxmpm perchild threadpool worker * You do not currently have any of these MPMs installed. * Please re-install apache with the correct mpm-* USE flag set. I successfully use mpm-itk with dev-lang/php-5.2.2-r1 without any problems. Why dev-lang/php-5.2.3-r3 must be different?
You either need to build both PHP and Apache w/ USE=threads, or none. mpm-itk is not a threaded MPM and you are trying to build PHP w/ USE=threads.