Copy stable/11@r303970 to releng/11.0 as part of the 11.0-RELEASE
cycle.

Prune svn:mergeinfo from the new branch, and rename it to RC1.

Update __FreeBSD_version.

Use the quarterly branch for the default FreeBSD.conf pkg(8) repo and
the dvd1.iso packages population.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Drop the 3rd clause from all 3 clause BSD licenses where I am the sole
holder to convert them to 2 clause BSD licenses.

MFC after: 1 week

Don't let hastd use C11 atomics.

Due to possible concerns about the stability of C11 atomics, use our
existing atomics API instead.

Requested by: pjd

Let hastd use C11 atomics.

C11 atomics now work on all the architectures. Have at least a single
piece of software in our base system that uses C11 atomics. This
somewhat makes it less likely that we break it because of LLVM imports,
etc.

Partially revert my last change.

I forgot that I still had a locally applied patch to my copy of Clang
that needs to be pushed in before we should use C11 atomics.

Use C11 <stdatomic.h> instead of our non-standard <machine/atomic.h>.

Reviewed by: pjd

- Add support for 'memsync' mode. This is the fastest replication mode that's
why it will now be the default.
- Bump protocol version to 2 and add backward compatibility for version 1.
- Allow to specify hosts by kern.hostid as well (in addition to hostname and
kern.hostuuid) in configuration file.

Sponsored by: Panzura
Tested by: trociny