Keep original value of "prototype"

Author: dstogov

ext/opcache/Optimizer/zend_optimizer.c

@@ -1561,9 +1561,11 @@ int zend_optimize_script(zend_script *script, zend_long optimization_level, zend
 
 				ZEND_ASSERT(orig_op_array != NULL);
 				if (orig_op_array != op_array) {
+					zend_function *prototype = op_array->prototype;
 					HashTable *ht = op_array->static_variables;
 
 					*op_array = *orig_op_array;
+					op_array->prototype = prototype;
 					op_array->static_variables = ht;
 				}
 			}