Add option to disable the "No ???.today" periodic messages (first run).
https://bugs.freenas.org/issues/3799
Merge branch 'periodic' of https://github.com/dlacko/trueos into feature/unified_freebsd
Make comcosole options set before its activation to be remembered.
Merge branch 'feature/unified_freebsd' of git://github.com/trueos/trueos into feature/unified_freebsd
MFC r229663: Allow to change vfs.zfs.arc_meta_limit at runtime.

- Change vfs.zfs.arc_meta_used from CTLFLAG_RDTUN to CTLFLAG_RD,
as it is not a tunable.

MFC slacker:	pjd
MFC r258294:
Fix ZFS deadlock when sending a snapshot which is mounted.

Approved by:	re (glebius)
Sponsored by:	Multiplay
ZFS/GFS handling fixes