dbus-sysdeps-win.c makes use of a constant called
PROCESS_QUERY_LIMITED_INFORMATION, which was added after Windows
XP.  There is code present to make sure the constant is not used
when running on an XP system, but the constant is still required
at build time.  Unfortunately, the Windows headers provided by
MinGW are old enough that they do not contain this constant, so
building with MinGW fails.

This patch adds a definition for the constant if one is not already
present.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=71366


Reviewed-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>
[altered comment to specify MinGW32 < 4, since mingw-w64
and MinGW 4.0+ do have this constant -smcv]