Reset trampoline on executor startup

Make sure the trampoline is usable, even if we had an unclean
shutdown on the last request.

Author: nikic

Zend/zend_execute_API.c

@@ -173,6 +173,7 @@ void init_executor(void) /* {{{ */
 	EG(prev_exception) = NULL;
 
 	EG(fake_scope) = NULL;
+	EG(trampoline).common.function_name = NULL;
 
 	EG(ht_iterators_count) = sizeof(EG(ht_iterators_slots)) / sizeof(HashTableIterator);
 	EG(ht_iterators_used) = 0;