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

builtin/worktree.c

@@ -626,6 +626,7 @@ static void print_preparing_worktree_line(int detach,
  * Returns 0 on failure and non-zero on success.
  */
 static int first_valid_ref(const char *refname UNUSED,
+			   const char *referent UNUSED,
 			   const struct object_id *oid UNUSED,
 			   int flags UNUSED,
 			   void *cb_data UNUSED)