git-repack: re-enable parsing of -n command line option

In commit 5715d0b (Migrate git-repack.sh to use git-rev-parse --parseopt,
2007-11-04), parsing of the '-n' command line option was accidentally lost
when git-repack.sh was migrated to use git-rev-parse --parseopt. This adds
it back.

Signed-off-by: A Large Angry SCM <gitzilla@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-repack.sh

@@ -11,6 +11,7 @@ a               pack everything in a single pack
 A               same as -a, and keep unreachable objects too
 d               remove redundant packs, and run git-prune-packed
 f               pass --no-reuse-delta to git-pack-objects
+n               do not run git-update-server-info
 q,quiet         be quiet
 l               pass --local to git-pack-objects
  Packing constraints