Quick compiler: fix Arm64 inline locking code

The Arm64 monitor enter code was incorrectly comparing the
thread ID to zero rather than the lock value to determine if the
inline fast path was doable.  As a result, we ended up always
using the out-of-line case.

This fix delivers a 6% improvement to DeltaBlue.

b/16707253

Change-Id: I499530da84beecf1f3f5c5ebb666e3eb12599ac0