/proc/uptime can become a container uptime in LXC containers
but the process start time is still relative to the boot time.

This means things like "newer than" or "older than" will be incorrect
in some containers, using clock_gettime() fixes this as its always the
hosts boot time.

References:
 https://bugs.debian.org/1066090
 https://gitlab.com/procps-ng/procps/-/commit/b5e19c1730bcc68d553f44b5585704e3c92267bf#83c45d853acc8384452b404946e4a0c484b16a4e



Signed-off-by: Craig Small <csmall@dropbear.xyz>