Dereferencing process-handles no longer waits on those processes

When handles created by proc_open() and popen() got destroyed they called waitpid() and waited for the process to exit. Now they only wait if they are explicitly closed with proc_close() or pclose().

Implements FR #46487
Move pclose_wait to the end of php_file_globals to maintain ABI BC

Pointed out by: johannes@
Add a test for FR #46487 (Dereferencing process-handles no longer waits on those processes)