make LocSharedLock::mRef ops atomic

The current share() and drop() calls are not thread
safe, which can cause memory heap correuption. This
changes the read / write ops to be atomic.

Bug: 37853905
Test: GPS incl. XTRA delete working on Pixel

Change-Id: Ic241d4573bdf2e58c4e264e97bd41b56f882c791
CRs-Fixed: 975372
1 file changed