dri3: use invalidate.

This doesn't change anything to the intel DRI3 implementation,
but enables the gallium implementation to use dri2.stamp instead
of relying on the stamp shared with the st backend.

Signed-off-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/glx/dri3_glx.c

@@ -1308,9 +1308,14 @@ static const __DRIimageLoaderExtension imageLoaderExtension = {
    .flushFrontBuffer    = dri3_flush_front_buffer,
 };
 
+const __DRIuseInvalidateExtension dri3UseInvalidate = {
+   .base = { __DRI_USE_INVALIDATE, 1 }
+};
+
 static const __DRIextension *loader_extensions[] = {
    &imageLoaderExtension.base,
    &systemTimeExtension.base,
+   &dri3UseInvalidate.base,
    NULL
 };
 
@@ -1384,6 +1389,8 @@ dri3_swap_buffers(__GLXDRIdrawable *pdraw, int64_t target_msc, int64_t divisor,
          ++(*priv->stamp);
    }
 
+   (*psc->f->invalidate)(priv->driDrawable);
+
    return ret;
 }