completion: bash: remove old compat wrappers

It's been eight years, more than enough time to move on.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -3480,18 +3480,6 @@ __git_complete ()
 		|| complete -o default -o nospace -F $wrapper $1
 }
 
-# wrapper for backwards compatibility
-_git ()
-{
-	__git_wrap__git_main
-}
-
-# wrapper for backwards compatibility
-_gitk ()
-{
-	__git_wrap__gitk_main
-}
-
 __git_complete git __git_main
 __git_complete gitk __gitk_main