This incorporates changes from https://golang.org/cl/123290043 and
https://golang.org/cl/127320043.

Files generated on Ubuntu Trusty.

Change-Id: I669c60714e857ef5f06515cd3b65dfc94785e179
Reviewed-on: https://go-review.googlesource.com/10060Reviewed-by: Rob Pike <r@golang.org>