t/helper: merge test-scrap-cache-tree into test-tool

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/helper/test-tool.c

@@ -31,6 +31,7 @@ static struct test_cmd cmds[] = {
 	{ "regex", cmd__regex },
 	{ "revision-walking", cmd__revision_walking },
 	{ "run-command", cmd__run_command },
+	{ "scrap-cache-tree", cmd__scrap_cache_tree },
 	{ "sha1", cmd__sha1 },
 };