vtn/opencl: add ctz support

ctz is a CL2.0 opcode but 3.0 requires it as well so just add support
for it.

Tested against CTS integer_ops integer_ctz test.

(long line broken up)

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7468>
2 files changed