gdkproperty-win32.c: Fix gtk-font-name handling

gdkproperty-win32.c: Fix gtk-font-name handling

...on Windows 8+ and when the system setting for non-Unicode programs do
not match the language version of Windows by falling back to using Pango.

This ensures that the correct font is used during these scenarios, so that
we minimize the risk of seeing garbled characters for texts that the system
code page does not support due to system peculiarties.  There might be a
way to support gtk-font-name handling using the native Windows APIs
directly on Windows 8+, but that needs to be investigated.

https://bugzilla.gnome.org/show_bug.cgi?id=726298