gas/doc fails to build with mingw

[Eli Zaretskii]

> From: Bill Morgan <arthurwilliammorgan@gmail.com>
> Date: Thu, 2 Aug 2018 08:42:49 -0500
> 
> I'm getting errors like this when building binutils-gdb (the gas doc is
> failing to build). Has anyone seen this before or know how to fix it?
> 
> /d/git/binutils-gdb/binutils-gdb-git/gas/doc/as.texi:635: table requires an
> argument: the formatter for @item

Line 635 is:

  @table @gcctabopt

And gcctabopt is defined near the beginning:

  @macro gcctabopt{body}
  @code{\body\}
  @end macro

So I wonder why this didn't work for you.  (And why are you building
Gas documentation while building GDB?)