- 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

Use thr_once() with once_t controls to initialize various thread_key_t
objects used to provide per-thread storage in the RPC code. Almost all
of these used double-checking with a dedicated mutex (tsd_lock) to do this
before. However, that is not always safe with more relaxed memory orders.
There were also other bugs, such as one in __rpc_createrr() that caused a
new key to be allocated each time __rpc_createrr() was invoked.

PR: threads/144558
Reported by: Sam Robb samrobb of averesystems com (key leak)
MFC after: 1 week

Don't do a time travel to 12006...

Staticize a couple of functions.

Remove a few unused locks.

Remove locks from application namespace.