configure: allow automatic enabling of several dependencies
configure: allow automatic enabling of several dependencies

Detect the presence of some optional features and enable or disable them
accordingly.

jonnylamb/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx