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

Address some WITNESS panics that occur when using the via driver.

Some of these cases should be safe in a non-atomic fashion, however
since all of the driver ioctls are locked, a lot of work is required to
fix it correctly. Just don't sleep now.

MFC after: 2 weeks

Import simple drm memory manager.

This is required for the VIA driver and at least some parts are needed
for GEM.

MFC after: 2 weeks