Added support for Mach high resolution time, using thread_info() for cpu time and host_get_clock_service(SYSTEM_CLOCK) for real time. Note that the resolution returned by clock_get_attributes for the system clock on OS X is very bad (10 ms), but the time values actually delivered appears to be much better (on nanosecond scale). Rev: src/configure.in:1.1072 Rev: src/rusage.c:1.51