Merge branch 'js/shortlog-sort-stably'

"git shortlog -n" relied on the underlying qsort() to be stable,
which shouldn't have.  Fixed.

* js/shortlog-sort-stably:
  shortlog: use a stable sort

builtin/shortlog.c

@@ -443,7 +443,7 @@ void shortlog_output(struct shortlog *log)
 	struct strbuf sb = STRBUF_INIT;
 
 	if (log->sort_by_number)
-		QSORT(log->list.items, log->list.nr,
+		STABLE_QSORT(log->list.items, log->list.nr,
 		      log->summary ? compare_by_counter : compare_by_list);
 	for (i = 0; i < log->list.nr; i++) {
 		const struct string_list_item *item = &log->list.items[i];