Buildfarm failures on woodlouse (in ecpg-check)

Hello,

my buildfarm animal woodlouse (Visual Studio 2013 on Windows 7) stopped
working correctly some months ago. After Tom kindly prodded me into
fixing it, I noticed that I had configured it to skip the ecpg-check
step because one of the tests in the "thread" section (not always the
same) nearly always failed.

I had set it up in circa 2015, so I reenabled the step to see whether
anything had changed since, and it started failing again.

Through some trial and error, and with the help of Microsoft's
Application Verifier tool, I found what I think is the cause: It looks
like the VS 2013 CRT's setlocale() function is not entirely thread-safe;
the heap debugging options make it crash when manipulating per-thread
locale state, and according to the comments surrounding that spot in the
CRT source, the developers were aware the code is fragile.

I crudely hacked a critical section around the setlocale() call in
pgwin32_setlocale(). After this change, the test does not crash, while
without it, it crashes every time.

If there is interest in fixing this issue that is apparently limited to
VS 2013, I will try and produce a proper patch. I notice, however, that
there is a pthread compatibility layer available that I have no
experience with at all, and I assume using it is preferred over straight
Win32?

My hack is attached; please feel free to tell me I'm on the wrong track.
To build correctly, it requires defining _WIN32_WINNT to be 0x600 or
above (and using an SDK that knows about InitOnceExecuteOnce()).

--
Christian