Use $(GlibEtcInstallRoot) when invoking glib-compile-schemas, as CopyDir
is not GlibInstallRoot for GTK+ (due to quoting issues), meaning that the
glib-compile-schemas tool may not be found in certain cases.
Issue pointed out by Ignacio Casal Quinteiro.
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.
