Clear last error before shutting down memory manager

The last error is allocated using ZMM, make sure it's cleared
beforehand.

It would probably be better to allocate it persistently outside
of requests.

main/main.c

@@ -2449,6 +2449,7 @@ void php_module_shutdown(void)
 
 	/* close down the ini config */
 	php_shutdown_config();
+	clear_last_error();
 
 #ifndef ZTS
 	zend_ini_shutdown();