mesa/st: Signal state changes when depth_clamp is emulated

mesa/st: Signal state changes when depth_clamp is emulated

v1 implemented by Erik Faye-Lund <erik.faye-lund@collabora.com>
v2: - Add GS and TES
    - fix constants state update flags (Erik)
v3: don't update rasterizer when depth_clamp is lowered (Erik)
v4: Correct NewDepthClamp and also set flags for NewClipControl (Erik)
v5: Also set shader_has_one_variant property acording to possible
   depth_clamp lowering (Marek)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Reviewed-by: Marek Olšák <marek.olsak@amd.com>