virgl: add BPTC support.

This just adds the guest checks for BPTC, the host renderer
also needs code to support these.

Signed-off-by: Dave Airlie <airlied@redhat.com>

src/gallium/drivers/virgl/virgl_screen.c

@@ -488,6 +488,9 @@ virgl_is_format_supported( struct pipe_screen *screen,
    if (format_desc->layout == UTIL_FORMAT_LAYOUT_RGTC) {
       goto out_lookup;
    }
+   if (format_desc->layout == UTIL_FORMAT_LAYOUT_BPTC) {
+      goto out_lookup;
+   }
 
    if (format == PIPE_FORMAT_R11G11B10_FLOAT) {
       goto out_lookup;