The CoglPango code falls under the COGL "jurisdiction"; this means
that it cannot include Clutter headers unless strictly necessary.
The CoglPangoRenderer code was using the CLUTTER_NOTE() macro. Now
that COGL has it's own COGL_NOTE() similar macro, CoglPango should
use that and avoid including clutter-debug.h (which pulls in
clutter-private.h which in turn pulls in clutter-actor.h).
A new flag, COGL_DEBUG_PANGO, has been added to the COGL debug
flags.