[lttng-dev] [GIT PULL v2] Regenerate the metadata file after a major NTP correction

[Julien Desfossez]

This patchset for LTTng 2.8 is composed of commits in lttng-tools and
lttng-modules it allows the user to regenerate the metadata file of a
running session. This allows to fix the NTP offset located in the
metadata after a major NTP correction. Works for kernel and per-uid UST
sessions, local or remote but not live.

Please pull from:
https://github.com/jdesfossez/lttng-tools-dev/tree/regenmeta
b12c6ba Tests for metadata regenerate
b0eb2fd Command metadata regenerate
5983098 Store the relay protocol version in the consumer_output
ce3ea6b Store the version of the tracer in the UID registry

https://github.com/jdesfossez/lttng-modules-dev/tree/regenmeta
a728303 Command to regenerate the metadata of a session

Changes from v1:
- Addressed Mathieu's comments
- Added documentation in the manpage for the new command
- Send the metadata version to the relay now
- Implemented the check on the relay protocol version before allowing
the command
- Still missing the MI but I can't seem to find the willpower to want to
do it, it will come as a separate commit if this gets merged next week.

These commits are on top of my seqnum branch which is now located on top
of Mathieu's staging-test-fixes-v2 branch.
When these branches will be merged in master, I will rebase on master as
well, but in the meantime it is now ready for review.

Julien