MSVC Builds: Add Script to Generate gtk-win32.rc

MSVC Builds: Add Script to Generate gtk-win32.rc

In bug 733773, gtk-win32.rc was removed from the dist in the attempt to
make the print dialog on Windows themed, so this script was added so that
the gtk-win32.rc file can be generated during the Visual Studio builds of
GTK+ from the autotools scripts.  This is also intended for filling in the
arch of the build for MSVC builds for the manifest that is also required
for fixing bug 733773.  Python is used as it is already needed for

This is done as a custom build rule in the Visual Studio projects so that
it is easy to clean and rebuild gtk-win32.rc upon an update.

https://bugzilla.gnome.org/show_bug.cgi?id=733773