ABI breakage in the gcr library

[Stef Walter <stefw collabora co uk>]

Just wanted to give a heads up about some ABI breakage in the gcr library.

This means that once this is merged, you'll need to update seahorse,
gnome-keyring and gcr in to git master in order to build.

I've made changes to GckAttributes to make them threadsafe. To do this
GckAttributes becomes immutable, and added a GckBuilder with supporting
functions.

In order to do this, certain functions are removed from the public ABI
of the Gck library. We've not yet made a guarantee of stability there,
and these functions are only used in gnome-keyring and seahorse.

 * Updated the libtool library version number.
 * Both gnome-keyring and seahorse git master updated depends.
 * Cleaned up and removed old deprecated functions as well, since
   this is an ABI breakage opportunity.

Cheers,

Stef