nir/opt_if: also rewrite uniform uses for read_invocation
No Foz-DB changes, but maybe it matters in the future because dxil-spirv will use read_invocation for WaveReadLaneFirst in fragment shaders.
No Foz-DB changes, but maybe it matters in the future because dxil-spirv will use read_invocation for WaveReadLaneFirst in fragment shaders.