Merge branch 'jk/unused-parameter'

Mark-up unused parameters in the code so that we can eventually
enable -Wunused-parameter by default.

* jk/unused-parameter:
  t/helper: mark unused callback void data parameters
  tag: mark unused parameters in each_tag_name_fn callbacks
  rev-parse: mark unused parameter in for_each_abbrev callback
  replace: mark unused parameter in each_mergetag_fn callback
  replace: mark unused parameter in ref callback
  merge-tree: mark unused parameter in traverse callback
  fsck: mark unused parameters in various fsck callbacks
  revisions: drop unused "opt" parameter in "tweak" callbacks
  count-objects: mark unused parameter in alternates callback
  am: mark unused keep_cr parameters
  http-push: mark unused parameter in xml callback
  http: mark unused parameters in curl callbacks
  do_for_each_ref_helper(): mark unused repository parameter
  test-ref-store: drop unimplemented reflog-expire command

object-file.c

@@ -2306,11 +2306,11 @@ int repo_has_object_file(struct repository *r,
  * report the minimal fsck error here, and rely on the caller to
  * give more context.
  */
-static int hash_format_check_report(struct fsck_options *opts,
-				     const struct object_id *oid,
-				     enum object_type object_type,
-				     enum fsck_msg_type msg_type,
-				     enum fsck_msg_id msg_id,
+static int hash_format_check_report(struct fsck_options *opts UNUSED,
+				     const struct object_id *oid UNUSED,
+				     enum object_type object_type UNUSED,
+				     enum fsck_msg_type msg_type UNUSED,
+				     enum fsck_msg_id msg_id UNUSED,
 				     const char *message)
 {
 	error(_("object fails fsck: %s"), message);