builtin/repack.c: move .idx files into place last

In a similar spirit as the previous patch, fix the identical problem
from `git repack` (which invokes `pack-objects` with a temporary
location for output, and then moves the files into their final locations
itself).

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

builtin/repack.c

@@ -208,10 +208,10 @@ static struct {
 	unsigned optional:1;
 } exts[] = {
 	{".pack"},
-	{".idx"},
 	{".rev", 1},
 	{".bitmap", 1},
 	{".promisor", 1},
+	{".idx"},
 };
 
 static unsigned populate_pack_exts(char *name)