- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add CPU percentage limit enforcement to RCTL. The resouce name is "pcpu".
It was implemented by Rudolf Tomori during Google Summer of Code 2012.

Make racct and rctl correctly handle jail renaming. Previously
they would continue using old name, the one jail was created with.

PR: bin/165207

Fix another bug introduced in r225641, which caused rctl to access certain
fields in 'struct proc' before they got initialized in do_fork().

MFC after: 3 days

Rename resource names to match these in login.conf.

Style fix - macros are supposed to be uppercase.

Remove definitions for RACCT_FSIZE and RACCT_SBSIZE - these two are rather
performance-sensitive and not that useful, so I won't be merging them
before 9.0.

Add racct. It's an API to keep per-process, per-jail, per-loginclass
and per-loginclass resource accounting information, to be used by the new
resource limits code. It's connected to the build, but the code that
actually calls the new functions will come later.

Sponsored by: The FreeBSD Foundation
Reviewed by: kib (earlier version)