Explicitly note that CLOCK_PROCESS_CPUTIME_ID and
CLOCK_PROCESS_CPUTIME_ID are not settable.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
.BR CLOCK_PROCESS_CPUTIME_ID " (since Linux 2.6.12)"
Per-process CPU-time clock
(measures CPU time consumed by all threads in the process).
+On Linux, this clock is not settable.
.TP
.BR CLOCK_THREAD_CPUTIME_ID " (since Linux 2.6.12)"
Thread-specific CPU-time clock.
+On Linux, this clock is not settable.
.SH RETURN VALUE
.BR clock_gettime (),
.BR clock_settime (),