commit 4814d3cb ("ui/dbus: restrict opengl to gbm-enabled config")
assumes that whenever GBM is available, OpenGL is. This is not always
the case, let's further restrict opengl-related paths and fix some
compilation issues.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230515132348.1024663-1-marcandre.lureau@redhat.com>