bug#28601: 26.0.50; configure: error: Emacs does not support 'x86_64-pc-msys' systems.

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Date: Thu, 16 Nov 2017 09:40:56 -0500
> Cc: Vincent Belaïche <vincent.belaiche@gmail.com>, 
>       Glenn Morris <rgm@gnu.org>, 28601@debbugs.gnu.org, Francis Wright 
> <f.j.wright@live.co.uk>, 
>       Stephen Leake <stephen_leake@stephe-leake.org>, Phillip Lord 
> <phillip.lord@russet.org.uk>, 
>       Fabrice Popineau <fabrice.popineau@gmail.com>
> 
> Here's an updated patch.

LGTM, thanks.