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

Style 9 changes.
MFC after: 1 Month

Remove redundant declaration for sysctl kern.

This is trying to fix the GCC build.

MFC after: 1 month
X-MFC-With: r290663

Add a kernel test framework. The callout_test is a demonstration and will only
work with the upcoming async-drain functionality. Tests can be added
to the tests directory and then the framework can be used to launch
those tests.

MFC after: 1 month
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D1755