Don't set IS_STR_PERMANENT flag for strings stored in the file cache (#15643)

Author: dstogov

ext/opcache/zend_persist.c

@@ -37,7 +37,8 @@
 
 #define zend_set_str_gc_flags(str) do { \
 	GC_SET_REFCOUNT(str, 2); \
-	if (file_cache_only) { \
+	if (file_cache_only \
+	 || (ZCG(current_persistent_script) && ZCG(current_persistent_script)->corrupted)) { \
 		GC_TYPE_INFO(str) = GC_STRING | (IS_STR_INTERNED << GC_FLAGS_SHIFT); \
 	} else { \
 		GC_TYPE_INFO(str) = GC_STRING | ((IS_STR_INTERNED | IS_STR_PERMANENT) << GC_FLAGS_SHIFT); \