Search also for the headers in include/gio-win32-2.0, as gio.h will
include those headers at some point, and arrange the include paths in a
dependency hierarchy style, top-to-down.
We need to rename the projects so that when these projects are added
into an all-in-one solution file that will build the GTK+ 2/3 stack,
the names of the projects will not collide with the GTK+-2.x ones,
especially as GTK+-2.x and GTK+-3.x are done to co-exist on the same
system. This is due to the case that the MSVC projects are directly
carried over from the GTK+-2.x ones and was then updated for 3.x.
We still need to update the GUIDs of the projects, so that they won't
conflict with the GTK+-2.x ones.
