Log Message:
libatomic_ops: updated to 7.6.8

Changes 7.6.8:
Eliminate 'casting signed to bigger unsigned int' CSA warning (test_stack)
Eliminate 'redundant blank line at start/end of block' CodeFactor warning
Fix 'Cannot implement CAS_full on this architecture' build error (nios2)
Fix a typo in arm_v6.h
Support aarch64-ilp32 (GCC) and UWP/arm64 (MS VC) targets
Undefine AO_ARM_HAVE_* private macros after their usage
Use standalone private macro to guard against AO_GCC_BARRIER redefinition
Workaround 'condition my_chunk_ptr is always false' cppcheck false positive