gallium/draw: Fix rasterizer_discard for wide points/lines.

Fixes the rasterizer_discard failures for softpipe, because the wide paths
(which we hit for points in the CTS) were dropping the discard state when
making the no_cull shadow state.

Cc: mesa-stable
Reviewed-by: Brian Paul <brianp@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7558>
(cherry picked from commit 0b4825c872558b1e21f6b9c6e8256482988ee243)
8 files changed