Fix byte_cas to use uintptr_t Atomic.
Fix byte_cas to use uintptr_t Atomic.

Previously we used int32_t Atomic with a uintptr_t bit shift.
This was a mismatch on 64 bit and resulted in occasionally
having the cas return without having succeeded.

Bug: 16819816

Change-Id: I10fa9c2f09ae8fe0997a4c9293fa123c6bde5920

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst