go.crypto/ssh/terminal: enable freebsd build

syscall.Termios, which was the only thing breaking the build, is
available in go tip now
(https://code.google.com/p/go/source/detail?r=873d664b00ec)

R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/51690043

Committer: Brad Fitzpatrick <bradfitz@golang.org>
undo CL 51690043 / abf8f8812575

Breaks FreeBSD build of subrepo for non-tip users.

««« original CL description
go.crypto/ssh/terminal: enable freebsd build

syscall.Termios, which was the only thing breaking the build, is
available in go tip now
(https://code.google.com/p/go/source/detail?r=873d664b00ec)

R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/51690043

Committer: Brad Fitzpatrick <bradfitz@golang.org>
»»»

R=golang-codereviews, dave
CC=golang-codereviews
https://codereview.appspot.com/51100044
go.crypto/ssh: import gosshnew.

See https://groups.google.com/d/msg/Golang-nuts/AoVxQ4bB5XQ/i8kpMxdbVlEJ

R=hanwen
CC=golang-codereviews
https://codereview.appspot.com/86190043
import license
add build tags for *BSD
readme