vbo: Move vbo_bind_arrays into a dd_driver_functions draw callback.

vbo: Move vbo_bind_arrays into a dd_driver_functions draw callback.

Factor out that common call into the almost single place.
Remove the _mesa_set_drawing_arrays call from vbo_{exec,save}_draw code
paths as the function is now called through vbo_bind_arrays.
Prepare updating the list of struct gl_vertex_array entries via
calling _vbo_update_inputs for being pushed into those drivers that
finally work on that long list of gl_vertex_array pointers.

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