s3: lib: In create_clock_itime(), use timespec_current() -> clock_gettime(CLOCK_REALT...

s3: lib: In create_clock_itime(), use timespec_current() -> clock_gettime(CLOCK_REALTIME..).

CLOCK_MONOTONIC (which we previously used) is reset
when the system is rebooted.

CLOCK_REALTIME is a "wall clock" time. It's still affected by NTP
changes (for Linux we should probably use CLOCK_TAI instead
but that is Linux-specific). For most systems CLOCK_REALTIME
will be good enough.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>