The previous detection was based on bits per pixel only and would
consider bpp >= 24 as X888 or 8888 24-bit color depth formats.
This commit ensures we now use the newly added
_cogl_util_pixel_format_from_masks() api that returns a CoglPixelFormat
according to channel masks and color depth. This helps to add support
for more pixel formats.
https://bugzilla.gnome.org/show_bug.cgi?id=660188
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Reviewed-by: Neil Roberts <neil@linux.intel.com>