Define new option, INACCURATE_MICROTIME_IS_OK. When this is defined,

Define new option, INACCURATE_MICROTIME_IS_OK.  When this is defined,
the NTP kernel PLL is disabled, and acquire_timer0() is enabled, thus
opening the door for microtime() (and hence gettimeofday()) to return
bogus timestamps.  This option is necessary for the `pca' driver to
work, but is implemented to underscore the fact that accurate timekeeping
and the `pca' driver are incompatible at present.  If someone writes a version
of microtime() that works when the `pca' driver is being used, this can get
junked.