G_DISABLE_DEPRECATED is only intended for developers of Cogl and it
sometimes breaks the build for people just trying to build a
release. This patch adds an option to enable deprecated Glib
features. By default it is enabled for non-git versions of Cogl.
The patch is based on similar code in Clutter except it adds the flags
to COGL_EXTRA_CFLAGS instead of having a separate variable.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
5aab8a2310