GVFS currently requires the gnome-1 libraries.
Switching it to use gnome-2 is trivial, requiring only
to change `#include <gnome.h>' to `#include
<libgnome/libgnome.h>' and removing a NULL argument
from one function call.
Most of this patch involves detecting the situation
where the user only has gnome-2 libraries installed,
and setting up the LD path and CFLAGS.