use -h for synopsis and --help for manpage consistently

A few scripted Porcelain implementations pretend as if the routine to show
their own help messages are triggered upon "git cmd --help", but a command
line parser of "git" will hijack such a request and shows the manpage for
the cmd subcommand.

Leaving the code to handle such input is simply misleading.

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-pull.sh

@@ -120,7 +120,7 @@ do
 	--d|--dr|--dry|--dry-|--dry-r|--dry-ru|--dry-run)
 		dry_run=--dry-run
 		;;
-	-h|--h|--he|--hel|--help|--help-|--help-a|--help-al|--help-all)
+	-h|--help-all)
 		usage
 		;;
 	*)