Merge branch 'jc/refs-symref-referent'

The refs API has been taught to give symref target information to
the users of ref iterators, allowing for-each-ref and friends to
avoid an extra ref_resolve_* API call per a symbolic ref.

* jc/refs-symref-referent:
  ref-filter: populate symref from iterator
  refs: add referent to each_ref_fn
  refs: keep track of unresolved reference value in iterators

t/helper/test-ref-store.c

@@ -156,7 +156,7 @@ static int cmd_rename_ref(struct ref_store *refs, const char **argv)
 	return refs_rename_ref(refs, oldref, newref, logmsg);
 }
 
-static int each_ref(const char *refname, const struct object_id *oid,
+static int each_ref(const char *refname, const char *referent UNUSED, const struct object_id *oid,
 		    int flags, void *cb_data UNUSED)
 {
 	printf("%s %s 0x%x\n", oid_to_hex(oid), refname, flags);