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 default leap-seconds file. This should help ntp networks get the
leap second date correct

Updates to the file can be obtained from ftp://time.nist.gov/pub/ or
ftp://tycho.usno.navy.mil/pub/ntp/.

Suggested by: dwmalone
Reviewed by: roberto, dwmalone, delphij
Approved by: roberto
MFC after: 1 week