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

1) Const enough things to avoid warnings.
2) Cast ifdef_level to a size_t before comparing it to a ratio of size_ts.
Ifdef_level should always be positive.
3) Complete prototype for chfont.
4) Cast some ptrdiff_ts to ints before using as a field width.
5) Avoid shadowing a local variable p with another local variable p.

Make this compile cleanly when warnings are enabled:
- ANSIfy function declarations
- braces around initializers structs within structs
- add parens in complicated expressions
- disambiguate dangling elses
- no more implicit int
- make functions static where possible
- use prototypes
- don't use varargs hack for diag()

Requested by: joerg
MFC after: 2 weeks