gmd/go: go get code.google.com/r/xxx support

[gopherbot]

by liuyuanzhi:

A cloned repository in googlecode with url pattern code.google.com/r/xxx
{{{
go get -u code.google.com/r/liuyuanzhi-goprotobuf/protoc-gen-go
package code.google.com/r/liuyuanzhi-goprotobuf/protoc-gen-go: invalid code.google.com/
import path "code.google.com/r/liuyuanzhi-goprotobuf/protoc-gen-go"
}}}
Which version are you using?  (run 'go version')
go version go1.1.1 darwin/amd64

Please provide any additional information below.
https://groups.google.com/forum/#!topic/golang-nuts/jYuuHiPjgTI

[robpike]

Comment 1:

Labels changed: added priority-someday, removed priority-triage.

Status changed to Accepted.

[robpike]

Comment 2:

Status changed to Duplicate.

Merged into issue #5408.