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
When using a context with robustness, glGetError() may return
GL_CONTEXT_LOST at any time and this error doesn't get cleared until
the application calls glGetGraphicsResetStatus() . This means that our
error checking can't call glGetError() in a loop without checking for
that return value and returning in that case.
https://bugzilla.gnome.org/show_bug.cgi?id=739178
