lib: internal: clock-snapshot-set.h: require logging

lib: internal: clock-snapshot-set.h: require logging

This patch makes the internal `clock-snapshot-set.h` require what it
needs instead of using the macros only if they exist. This makes it
impossible to skip logging in this header.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: Ib8b3def2869ab214a3d38e3a1cea7b9954fc056c
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1578
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>