- 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

Modify ipxsocket regression test to create and close sockets several
times, with variable length sleeps between socket() and close(). This
will help to ensure that IPX/SPX timers fire while the sockets are
open, and hence have PCB's on the IPX pcb list, so that if timers are
going to stumble over PCB types they don't expect, it will happen as
part of this test.

Add simple ipxsocket regression test: open, and close, various IPX socket
types supported by the FreeBSD netipx implementation.