mesa: Work with bitmasks when en/dis-abling VAO arrays.

mesa: Work with bitmasks when en/dis-abling VAO arrays.

For enabling or disabling VAO arrays it is now possible to
change a set of arrays with a single call without the need to
iterate the attributes.
Make use of this technique in the vao module.

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich@web.de>