gallium: remove support for predicates from TGSI (v2)

Neved used.

v2: gallivm: rename "pred" -> "exec_mask"
    etnaviv: remove the cap
    gallium: fix tgsi_instruction::Padding

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
36 files changed