gas/doc fails to build with mingw

[Eli Zaretskii]

> From: Bill Morgan <arthurwilliammorgan@gmail.com>
> Date: Thu, 2 Aug 2018 10:09:30 -0500
> Cc: gdb@sourceware.org
> 
>  So I wonder why this didn't work for you. 
> 
> Line endings. Apparently the msys2 version of texi2info doesn't like CRLF in texi files, because if I change
> them, then it works.

Ah, that one.  One more reason for me not to use MSYS2 Texinfo, I
guess...