Group all the three config files from clutter/cogl/meta into one
and also remove unnused configurations and replace duplicated ones
This also fixes Cogl usage of HAS_X11/HAS_XLIB to match the expected
build options
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3368>
Make CoglBuffer an abstract class and inherit the various Cogl*Buffer types from it.
As none of the subclasses is overriding the vtable functions, they were not turned into
vfuncs but plain function pointers in CoglBuffer.
We still use _cogl_buffer_initialize until we port the various params into actual construct-only
properties, similar to the previous commit for CoglTexture.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3193>
In cogl use cogl-config.h and in clutter use clutter-build-config.h. We
can't use clutter-config.h in clutter because its already used and
installed.
https://bugzilla.gnome.org/show_bug.cgi?id=768976
