simplied the fix to FreeBSD-SA-04:06.ipv6.  The previous one worried too much even though we actually validate the parameters.  This code also is more compatible with other *BSDs, which do copyin within setsockopt().
simplied the fix to FreeBSD-SA-04:06.ipv6.  The previous one worried
too much even though we actually validate the parameters.  This code
also is more compatible with other *BSDs, which do copyin within
setsockopt().

Submitted by:	Keiichi SHIMA <keiichi__at__iijlab.net>
Reviewed by:	security-officer (nectar)
Obtained from:	KAME

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase