pkg/build: load the SCTP and IPSec stacks on FreeBSD
pkg/build: load the SCTP and IPSec stacks on FreeBSD

IPSec is not compiled into GENERIC kernels and must be loaded.  SCTP
currently is compiled into GENERIC, but this is expected to change.

google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller