Legacy FS shaders may use glColor and glSecondaryColor without the VS
actually emitting it. However, on GLES the interfaces between stages must
be matched, so replace FS input colors with a constant when they are not
emitted by the VS.
v2: - revert how the color_in_mask is populated
- handle back color too
- correctly appply the interface matching only on GLES (Bug reported
by David Riley).
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: John Bates <jbates@chromium.org>