This change adds support for Solaris.

To read and write IPv6 ancillary data using ControlMessage, ipv6 pacakge
requires https://go-review.googlesource.com/30171/

Note: Unlike other platforms, Solaris seems to have a few restrictions
on ICMP property access via raw IP sockets. At least applications are
prohibited from using IPV6_CHECKSUM option for ICMP transport.

Fixes golang/go#17324.

Change-Id: Ie014665d94ae6e4955c95d3eea88db90332e20bd
Reviewed-on: https://go-review.googlesource.com/30176
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>