Fix hashCode() for the read barrier lock word change.

Mask the low 28 bits of the lock word.

This is a cherrypick of commit 28da248e817762ef6e2709a8379228867862d97a
from libart/ to ojluni/.

Bug: 25838574
Bug: 19355854
Bug: 12687968
Change-Id: I436a8bc13f7729300a01c0558cccb5cf6c40bdf8
1 file changed