Prevent test case from stalling

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.

Author: cmb69

sapi/cli/tests/sapi_windows_set_ctrl_handler.phpt

@@ -56,11 +56,13 @@ if ($is_child) {
 	$status = proc_get_status($proc);
 	if ($status["running"]) {
 		echo "Child $child_pid didn't exit after ${max}us\n";
+		foreach ($pipes as $pipe) {
+			fclose($pipe);
+		}
+		proc_terminate($proc);
 	} else {
 		echo "Child $child_pid exit with status ", $status["exitcode"], " after ${total}us\n"; 
 	}
-
-	proc_close($proc);
 }
 
 function get_evt_name(int $evt) : ?string