- 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

Fix build issue and incompatibilites introduced by r283620.

- Re-introduce "device ixgbe" option for kernel configs. This allows
users to continue using existing kernel configurations, while still
letting if_ix and if_ixv exist to allow ifconfig magic to work.
Though the amd64 GENERIC config has "device ix" and "device ixv" instead of
"device ixgbe".

This is achieved by making the if_ixgbe module a stub that depends
on if_ix and if_ixv.

- Replace if_baudrate assignment with if_initbaudrate() call.

Thanks to jhb@ for the stub module suggestion and pointing out the if_baudrate
error.

Approved by: jfv (mentor)