for-each-ref: remove unused variable

No code ever used this symbol since the command was introduced at
9f613ddd (Add git-for-each-ref: helper for language bindings,
2006-09-15).

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/for-each-ref.c

@@ -89,7 +89,7 @@ static struct {
  */
 static const char **used_atom;
 static cmp_type *used_atom_type;
-static int used_atom_cnt, sort_atom_limit, need_tagged, need_symref;
+static int used_atom_cnt, need_tagged, need_symref;
 
 /*
  * Used to parse format string and sort specifiers
@@ -1037,7 +1037,6 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 
 	if (!sort)
 		sort = default_sort();
-	sort_atom_limit = used_atom_cnt;
 
 	/* for warn_ambiguous_refs */
 	git_config(git_default_config, NULL);