Merge branch 'jk/unused-annotation'

Annotate function parameters that are not used (but cannot be
removed for structural reasons), to prepare us to later compile
with -Wunused warning turned on.

* jk/unused-annotation:
  is_path_owned_by_current_uid(): mark "report" parameter as unused
  run-command: mark unused async callback parameters
  mark unused read_tree_recursive() callback parameters
  hashmap: mark unused callback parameters
  config: mark unused callback parameters
  streaming: mark unused virtual method parameters
  transport: mark bundle transport_options as unused
  refs: mark unused virtual method parameters
  refs: mark unused reflog callback parameters
  refs: mark unused each_ref_fn parameters
  git-compat-util: add UNUSED macro

attr.c

@@ -61,10 +61,10 @@ struct attr_hash_entry {
 };
 
 /* attr_hashmap comparison function */
-static int attr_hash_entry_cmp(const void *unused_cmp_data,
+static int attr_hash_entry_cmp(const void *UNUSED(cmp_data),
 			       const struct hashmap_entry *eptr,
 			       const struct hashmap_entry *entry_or_key,
-			       const void *unused_keydata)
+			       const void *UNUSED(keydata))
 {
 	const struct attr_hash_entry *a, *b;