Merge branch 'jk/unused-post-2.39'

Code clean-up around unused function parameters.

* jk/unused-post-2.39:
  userdiff: mark unused parameter in internal callback
  list-objects-filter: mark unused parameters in virtual functions
  diff: mark unused parameters in callbacks
  xdiff: mark unused parameter in xdl_call_hunk_func()
  xdiff: drop unused parameter in def_ff()
  ws: drop unused parameter from ws_blank_line()
  list-objects: drop process_gitlink() function
  blob: drop unused parts of parse_blob_buffer()
  ls-refs: use repository parameter to iterate refs

builtin/merge.c

@@ -776,7 +776,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 }
 
 static void count_diff_files(struct diff_queue_struct *q,
-			     struct diff_options *opt, void *data)
+			     struct diff_options *opt UNUSED, void *data)
 {
 	int *count = data;