* rtems/Makefile.am, rtems/include/rtems/rtems/clock.h,
score/include/rtems/score/watchdog.h: Add support for a handler to
obtain the number of nanoseconds since the last clock tick. The
primary interface for this is rtems_clock_set_nanoseconds_extension.
Subsequent commits from Joel will redo the TOD support to use this
capability.
* rtems/src/clocksetnsecshandler.c: New file.