bug#8379: The width of linum window is not adjusted afterface-remapping

["Drew Adams" <drew.adams@oracle.com>]

> > I found that the width of linum window is not changed with
> > (text-scale-increase) or (text-scale-decrease) function.
> 
> This is bug#1255: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=1255

Well if Emacs Dev now recognizes that this is a bug or a missing feature (Stefan
called the _lack_ of window resizing for text scaling "one of its greatest
features"), there's a simple solution.  I proposed it as soon as text scaling
was introduced, but it wasn't adopted.

http://www.emacswiki.org/emacs/face-remap%2b.el

This provides an option that allows for automatic resizing of the window, to go
along with text resizing.  That puts the behavior under user control.  The
window resizing can be: none, horizontal, vertical, or both.

And any function or mode (e.g. linum-mode) that needs a particular type of
window resizing can obviously bind or set the value locally.

This is a trivial fix.  It would be good if Emacs Dev gives users the choice.
Here is the original thread, with a patch:
http://lists.gnu.org/archive/html/emacs-devel/2009-08/msg00414.html