bug#36337: 26.1; XBM images are sometimes not displayed correctly

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Sun, 30 Jun 2019 15:36:17 +0000
> Cc: triska@metalevel.at, 36337@debbugs.gnu.org
> 
> On Sun, Jun 30, 2019 at 3:15 PM Eli Zaretskii <eliz@gnu.org> wrote:
> > > Thanks, but maybe @w{@code{@var{stride} * @var{height}}} would be more 
> > > correct?
> >
> > Yes, of course.
> 
> Okay, I wasn't sure. Updated patch attached.

You removed the @w{...}, which IMO is important with long
expressions.  Other than that, looks good.