Check if restart is pending before trying to lock SHM

This reduces lock contention when Opcache restart is scheduled
but not yet started.

Closes phpGH-11805

Author: Mikhail Galanin

ext/opcache/zend_file_cache.c

@@ -1868,6 +1868,7 @@ zend_persistent_script *zend_file_cache_script_load(zend_file_handle *file_handl
 
 	if (!file_cache_only &&
 	    !ZCSG(restart_in_progress) &&
+	    !ZCSG(restart_pending) &&
 		!ZSMMG(memory_exhausted) &&
 	    accelerator_shm_read_lock() == SUCCESS) {
 		/* exclusive lock */