Fix wrong size calculation related to function name

It would be nice if we could drop this manual function name reuse
code altogether and rely on interning for it.

Author: nikic

ext/opcache/zend_persist_calc.c

@@ -192,13 +192,11 @@ static void zend_persist_op_array_calc_ex(zend_op_array *op_array)
 
 	if (op_array->function_name) {
 		zend_string *old_name = op_array->function_name;
-		zend_string *new_name = zend_shared_alloc_get_xlat_entry(old_name);
-
-		if (new_name) {
-			op_array->function_name = new_name;
-		} else {
+		if (!zend_shared_alloc_get_xlat_entry(old_name)) {
 			ADD_INTERNED_STRING(op_array->function_name);
-			zend_shared_alloc_register_xlat_entry(old_name, op_array->function_name);
+			if (!zend_shared_alloc_get_xlat_entry(op_array->function_name)) {
+				zend_shared_alloc_register_xlat_entry(old_name, op_array->function_name);
+			}
 		}
     }