automerge from 5.1-bugteam: Bug#52172 post-push fix: init auto-variable to NULL

dbug/dbug.c

@@ -2370,7 +2370,7 @@ static void DbugFlush(CODE_STATE *cs)
 
 void _db_flush_()
 {
-  CODE_STATE *cs;
+  CODE_STATE *cs= NULL;
   get_code_state_or_return;
   (void) fflush(cs->stack->out_file);
 }