Avoid loading to a general purpose register if the bit pattern consists
of a consecutive block of 1 bits.

Drive-by: Change a parameter from int8_t to byte such that the AVX_OP
macro works on these methods.

R=mstarzinger@chromium.org

Change-Id: Ib469ddd29d92ddeabe98460d2951b01159a6548a
Reviewed-on: https://chromium-review.googlesource.com/969123
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52077}