mesa: Clamp some depth values in glClearBufferfi

OpenGL 3.0 spec, section 4.2.3 "Clearing the Buffers":

   depth and stencil are the values to clear the depth and stencil
   buffers to, respectively. Clamping and type conversion for
   fixed-point depth buffers are performed in the same fashion as for
   ClearDepth.

Enables iris to pass the clearbuffer-depth-stencil piglit test.

Cc: mesa-stable
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7410>
(cherry picked from commit 2e713313a29422b38435c91f8277c1893fcad095)
2 files changed