Use the Python script that was used to create gtk-win32.rc from
gtk-win32.rc.in to similarly create libgtk3.manifest. As the wildcard
character can be used for all architectures, use that.
The libgtk3.manifest file needs to be specified explicitly in the projects,
so that it will be recognized and built into the GTK dll, so update the
project files as well on this part.
https://bugzilla.gnome.org/show_bug.cgi?id=733773