void vrend_set_sample_mask(UNUSED struct vrend_context *ctx, unsigned sample_mask)
{
   if (has_feature(feat_sample_mask))
      glSampleMaski(0, sample_mask);
}
void vrend_set_sample_mask(UNUSED struct vrend_context *ctx, unsigned sample_mask)
{
   if (has_feature(feat_sample_mask))
      glSampleMaski(0, sample_mask);
}