bug#2873: Keybinding info for remapped commands could be more useful

[Drew Adams]

> > >> When using a command, Emacs conveniently flashes the keybinding.
> > >> For remapped commands, the message is not as useful:
> > >> You can run the command `command' with <remap> <original-command>
> > >> 
> > >> It would probably be better to offer the binding of 
> > >> original-command instead.
> > 
> > > Sounds related to bug #788, which mentioned the same 
> > > problem for key mentions in menu items.
> > 
> > Indeed.  Back then I suggested to move the fix into 
> > where-is-internal and this bug report seems to show that
> > it would indeed be a good idea.
> 
> Yidong recently made a temporary fix of #788: removing the 
> key mention from such menu items. If and when the bug gets
> fixed properly, we need to remember to revert that temporary
> fix, so such keys will appear again (but properly) in menu
> items. 

BTW, somehow we already DTRT for `C-h f bar', for a command `bar' that is
remapped from command `foo'. The key bindings mentioned for `bar' are correct -
it doesn't just say that `bar' is remapped from `foo'.