Separate the base and ui parts of the Gcr library more thoroughly.
* This is due to gobject introspection not being able to have separate
GIRs provide the same namespace, and the desire to conditionally
build the GTK+ dependent stuff.
* Partially based on a patch by Mathias Hasselmann
* Separate GIRs: Gcr and GcrUi
* Separate libraries: libgcr-base-3.so and libgcr-ui-3.so. The latter
links to the former.
* Symlink libgcr-3.so to libgcr-ui-3.so
* Expose internal symbols in libgcr-base-3.so so they can be easily
shared by libgcr-ui-3.so
* Add --without-gtk argument
https://bugzilla.gnome.org/show_bug.cgi?id=688678