virgl: Add workaround for virglrenderer bug with handling of CMP and UCMP
GLSL-to-TGSI was emitting some MOVs to temporary variables but NTT is optimizing these MOVs away which lead to issue on vrend side where it expects the input to be floats.
Two dEQP-GLES31 tests are failing and will be fixed in virgl/virglrenderer!684 (merged)