completion: use __gitcomp_builtin in _git_ls_files

The new completable options are:

--debug
--empty-directory
--eol
--recurse-submodules
--resolve-undo

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

contrib/completion/git-completion.bash

@@ -1616,13 +1616,7 @@ _git_ls_files ()
 {
 	case "$cur" in
 	--*)
-		__gitcomp "--cached --deleted --modified --others --ignored
+		__gitcomp_builtin ls-files "--no-empty-directory"
-			--stage --directory --no-empty-directory --unmerged
-			--killed --exclude= --exclude-from=
-			--exclude-per-directory= --exclude-standard
-			--error-unmatch --with-tree= --full-name
-			--abbrev --ignored --exclude-per-directory
-			"
 		return
 		;;
 	esac