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

Add Performance Monitoring Counters support for AArch64.
Family-common and CPU-specific counters implemented.

Supported CPUs: ARM Cortex A53/57/72.

Reviewed by: andrew, bz, emaste, gnn, jhb
Sponsored by: ARM Limited
Differential Revision: https://reviews.freebsd.org/D2555