nvir/gv100: initial support

nvir/gv100: initial support

v2:
- add TargetGV100::isBarrierRequired() for OP_BREV
- use NV50_IR_SUBOP_LOP3_LUT() convenience macro where it makes sense
- separated out nir_lower_idiv into its own commit
- make use of the shared function to generate compiler options
- disable lower_fpow, nir's lowering is broken
v3:
- use replaceCvt() instead of custom NEG/ABS/SAT lowering
v4:
- remove WAR from peephole, not needed now we're using replaceCvt()

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5377>