Add zend_test_crash funtion to segfault PHP process

This is useful for testing PHP-FPM handling of crashed children.

Closes GH-11082

Skip pcntl_rfork() in arginfo test

Same as pcntl_fork(), we don't want to have this side-effect in
this mass-test.

Run arginfo/ZPP verification tests in strict mode as well

Closes GH-6370