bug#7662: 24.0.50; Keybindings for menu items not aligned

[Eli Zaretskii]

> From: Eli Zaretskii <eliz@gnu.org>
> Date: Tue, 21 Dec 2010 07:22:54 -0500
> Cc: 7662@debbugs.gnu.org
> 
>   Undo     C-x u
>   Cut      C-w
>   Copy     M-w
>   Paste    C-y
> 
> but instead I see this:
> 
>   Undo     C-x u
>   Cut      C-w
>   Copy    M-w    <<<<<<<<<<<<<<<<<<<<<<<<<
>   Paste    C-y

Bug squashed.  It affected all menu items that had an explicit `:keys'
attribute: we weren't prepending 2 spaces to the key sequence, like we
did when no `:keys' were present.  E.g., try Texinfo->Update All in
Texinfo mode.

This bug exists in Emacs 23 as well, so I fixed it on the emacs-23
branch (revno 100332).