Unfortunately FreeBSD 10 has changed its syscall arguments for
some reasons but as per request at golang-dev this CL does not
generate some structures, syscall numbers and constants as
compatible to FreeBSD 10 as follows:

Structure: Stat_t, IfData, IfMsghdr are based on 8-STABLE
Syscall number: Capsicum API is based on 9-STABLE
Constant: IFT_CARP, SIOCAIFADDR, SIOCSIFPHYADDR are based on 9-STABLE

Update #7193

FreeBSD 10 breaking changes:

r205792: Rename st_*timespec fields to st_*tim for POSIX 2008
compliance.
http://svnweb.freebsd.org/base?view=revision&revision=205792

r254804: Restructure the mbuf pkthdr to make it fit for upcoming
capabilities and features.
http://svnweb.freebsd.org/base?view=revision&revision=254804

r255219: Change the cap_rights_t type from uint64_t to a structure
that we can extend in the future in a backward compatible (API and
ABI) way.
http://svnweb.freebsd.org/base?view=revision&revision=255219

LGTM=iant
R=golang-codereviews, rsc, minux.ma, gobot, iant
CC=golang-codereviews
https://golang.org/cl/56770044