- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
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

Make iclear return int, since that matches all function definitions of it.

Add method enabled() to the SCC interface. This method can be used
by driver backends to mark individual channels as enabled or not.
The default implementation of this method always mark channels as
enabled.
This method is currently not used, but is added with the PowerQUICC
in mind where the 2nd SCC channel can be disabled.

Add scc(4), a driver for serial communications controllers. These
controllers typically have multiple channels and support a number
of serial communications protocols. The scc(4) driver is itself
an umbrella driver that delegates the control over each channel
and mode to a subordinate driver (like uart(4)).
The scc(4) driver supports the Siemens SAB 82532 and the Zilog
Z8530 and replaces puc(4) for these devices.