Pick the color 0xCC336699 as AARRGGBB, as if blended on black. This is
the color used with developing the sub-surface shot tests.
No other big reason than it should not be black to have better chances
of catching blending problems.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Micah Fedke <micah.fedke@collabora.co.uk>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>