xinetd: use monotonic time

xinetd: use monotonic time

When using xinet.d to limit rsync connections, it can't handle changes
in system time. When time is set back, the connection limit is reached
very quickly and rsync gets deactivated, if time is changed again, rsync
is never reactivated.

The current timer of xinet.d is based on the time() and is affected by
the system time. Use clock_gettime() with CLOCK_MONOTONIC as the new
timer because CLOCK_MONOTONIC clock is not affected by discontinuous
jumps in the system time.

Signed-off-by: Li Wang <li.wang@windriver.com>
Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>