Add sched_yield to the arm64 policy

sched_yield is used by the various Sanitizers. It is present for arm, x86 and
x86_64 but is missing for arm64.

Bug: 63907455
Test: built & run with Scudo locally enabled for media.extractor
Change-Id: I4ad9cfcd2bda2489858146dca7427e3719491e12