completion: use __gitcomp_builtin in _git_clone

The new completable options are:

--config
--dissociate
--ipv4
--ipv6
--jobs=
--progress
--reference-if-able
--separate-git-dir=
--shallow-exclude
--shallow-since=
--verbose

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

contrib/completion/git-completion.bash

@@ -1320,26 +1320,7 @@ _git_clone ()
 {
 	case "$cur" in
 	--*)
-		__gitcomp "
+		__gitcomp_builtin clone "--no-single-branch"
-			--local
-			--no-hardlinks
-			--shared
-			--reference
-			--quiet
-			--no-checkout
-			--bare
-			--mirror
-			--origin
-			--upload-pack
-			--template=
-			--depth
-			--single-branch
-			--no-tags
-			--branch
-			--recurse-submodules
-			--no-single-branch
-			--shallow-submodules
-			"
 		return
 		;;
 	esac