bug#25875: 26.0.50; Hang logging out of MS-Windows

[Richard Copley <rcopley@gmail.com>]

>>> Configured using:
>>>  'configure --prefix=/mingw64 --with-modules
>>>  --enable-locallisppath=/c/emacs/site-lisp
>>>  CPPFLAGS=-D_WIN32_WINNT=_WIN32_WINNT_WIN7 'CFLAGS=-O0 -g -ggdb''
>>
>> Why are you setting _WIN32_WINNT to this value when compiling Emacs?
>
> It's part of a patch that sets the AppUserModelID of the Emacs
> process and of the shortcut created by addpm.exe to the same
> string, so that if I pin the shortcut to the taskbar, that icon
> will combine with the taskbar button of a running Emacs process.
> I can't imagine it's relevant to this issue.
>
> [Would you like to see the patch? It would only be a starting point,
> since it wouldn't compile on earlier versions of the OS in its
> current state. And I'm still not ready to assign copyright.]

Hmm, that doesn't make much sense, does it? I only need those
flags in addpm.c, not for the rest of Emacs. Perhaps it's left over
from another experiment. I've taken it out of my build script, but
I haven't rebuilt because current master doesn't build from pristine:

+ ./autogen.sh
Checking whether you have the necessary tools...
(Read INSTALL.REPO for more details on building Emacs)
Checking for autoconf (need at least version 2.65) ... ok
Checking for automake (need at least version 1.11) ... ok
Your system has the required tools.
Inferring nt/gnulib.mk from lib/gnulib.mk ...
Running 'autoreconf -fi -I m4' ...
aclocal-1.15: error: aclocal: file
'/msys64/usr/share/aclocal/xsize.m4' does not exist
autoreconf: aclocal failed with exit status: 1