Use single version of double exported functions

Solve double export issue of some functions between spice-gtk and spice-glib libraries.

Some functions are exported by both spice-gtk and spice-glib. As the state of these function can be duplicate this can create some issues. Specifically you can enable debug but get only partly enabled.

So to solve this and have a consistent behaviour across system add new functions in spice-glib (where these functions where supposed to be) and use them (we need to keep providing old functions for ABI compatibility).