If the CTRL-C event can't be sent to the child for whatever reason, the
test will never terminate, because `proc_close()` waits for an infinite
amount of time. Therefore, we `proc_terminate()` the child instead,
after explicitly closing the pipes.
There is no reason to expect a `1` after the PID; neither the session
ID nor the memory usage are required to contain one. Actually, we just
want to verify here, that the process with the $child_pid is running,
and is a php.exe process.
php_win32_signal_system_ctrl_handler() is called from a kernel thread,
so the former initialization of `vm_interrupt_flag` has no effect,
since it is defined as thread-local. This is, however, not necessary,
since the CTRL signal handling is supposed to work only for the main
thread anyway. We therefore change `vm_interrupt_flag` and the related
variables to true globals.
This also allows us to unmark the respective test case as XFAIL.
Furthermore, `vm_interrupt_flag` is declared as `zend_bool *`, so we
better treat it such.
