XSI_ADVANCED_REALTIME
The XSI_ADVANCED_REALTIME option group indicates that the
_POSIX_CLOCK_SELECTION,
_POSIX_CPUTIME, and
_POSIX_MONOTONIC_CLOCK options are enabled.
Enable this option group with CONFIG_XSI_ADVANCED_REALTIME.
An implementation that claims conformance to this option group shall also support the POSIX_TIMERS option group.