libconfig problem in Windows binary packages

[Ethan A M. <sf...@us...>]

Bug report #2069 describes a gnuplot failure that I believe I have traced to
a bad (buggy) version of libconfig in the WIndows packages.

Gnuplot bug tracker:
    https://sourceforge.net/p/gnuplot/bugs/2069/

libconfig bug reports elsewhere
    https://bugs.gentoo.org/650332
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=895470
    https://bugs.freedesktop.org/show_bug.cgi?id=105492

As I understand the upstream descriptions, libconfig version 2.13.0
incorrectly resets the locale to the system default.  This overwrites
whatever the program has set.  In gnuplot's case this means that
after a call to libconfig the working LC_NUMERIC environment is
no longer "C".  If the default environment uses comma rather than
period for a decimal point, tbad things happen.

So far as I can tell, this error is still present in the current git repository
for libfontconfig, so you must downgrade (rather than upgrade) to get
a working library.  There is an item in the README for version 2.13.1
that says this has been fixed, but when I look at the source that doesn't
seem to be true. 

I recall that there was discussion earlier this year about whether
the fontconfig library and tools should be included in the Windows
gnuplot packages.  At the time there was no strong argument 
against including it.    But if the current libconfig is not reliable,
maybe the discussion should be re-opened?

	Ethan