mac thread_clock implementation
re-try QueryPerformanceCounter when failed.
undef BOOST_CHRONO_HAS_THREAD_CLOCK if defined(__hpux).
fix issue with process_cpu_clock having different behavior than the associated process_cpu_clock_ clocks.
make use of duration_values<common_type_t>::zero() instead of 0.
take care of process_cpu_clock on io v2. Input is not working yet.
Avoid the use of gmtime with Android as not available.
Try to fix #9720.