patch-ids.c: use ALLOC_GROW() in add_commit()

Signed-off-by: Dmitry S. Dolzhenko <dmitrys.dolzhenko@yandex.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/patch-ids.c b/patch-ids.c
index bc8a28f..bf81b92 100644
--- a/patch-ids.c
+++ b/patch-ids.c
@@ -83,10 +83,7 @@
 	ent = &bucket->bucket[bucket->nr++];
 	hashcpy(ent->patch_id, sha1);
 
-	if (ids->alloc <= ids->nr) {
-		ids->alloc = alloc_nr(ids->nr);
-		ids->table = xrealloc(ids->table, sizeof(ent) * ids->alloc);
-	}
+	ALLOC_GROW(ids->table, ids->nr + 1, ids->alloc);
 	if (pos < ids->nr)
 		memmove(ids->table + pos + 1, ids->table + pos,
 			sizeof(ent) * (ids->nr - pos));