mesa: skip extra state updates for clear calls

mesa: skip extra state updates for clear calls

The glClear call updates draw state in the same way as other draw calls
with _mesa_update_state func

If currently used shader uses textures, _mesa_update_state will try to
update the shader texture state

But if the texture not set yet, before glClear call, it will detect
incompleted texture and will create dummy texture with default values
(see the update_single_program_texture func).
And this will be complete waste of time for glClear

Closes: #7128

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18459>