Remove useless zval_ptr_dtor() in php_userstreamop_write()

At this point, retval is either false or converted to a long.

main/streams/userspace.c

@@ -602,8 +602,6 @@ static ssize_t php_userstreamop_write(php_stream *stream, const char *buf, size_
 		didwrite = count;
 	}
 
-	zval_ptr_dtor(&retval);
-
 	return didwrite;
 }