Pacify signed warning; ref #3565

src/hash.c

@@ -750,7 +750,8 @@ MRB_API mrb_value
 mrb_hash_keys(mrb_state *mrb, mrb_value hash)
 {
   khash_t(ht) *h = RHASH_TBL(hash);
-  khiter_t k, end;
+  khiter_t k;
+  mrb_int end;
   mrb_value ary;
   mrb_value *p;