zink: enable texture-buffer objects

This seems to work as-is, and just need enabling. There's a few piglit
failures, but those seems to be problems with the tests, where they
don't handle lacking GL3-support.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3647>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3647>

src/gallium/drivers/zink/zink_screen.c

@@ -176,6 +176,12 @@ zink_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_CUBE_MAP_ARRAY:
       return screen->feats.imageCubeArray;
 
+   case PIPE_CAP_TEXTURE_BUFFER_OBJECTS:
+      return 1;
+
+   case PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT:
+      return screen->props.limits.minTexelBufferOffsetAlignment;
+
    case PIPE_CAP_PREFER_BLIT_BASED_TEXTURE_TRANSFER:
       return 0; /* unsure */