net/rpc: add client support for RPC over HTTPS

[Adam Thomason]

While net/rpc supports HTTPS trivially in the server, there's no built-in way for a
client to connect to one since rpc.DialHTTPPath calls net.Dial itself. With some
duplicated code from client.go it's possible to create a working DialHTTPSPath in user
code, though this is suboptimal since DialHTTPPath references an unexported package
variable which must be duplicated.

https://golang.org/cl/100140043 implements rpc.DialHTTPS and rpc.DialHTTPSPath
which are exact analogues to DialHTTP and DialHTTPPath apart from also accepting a
tls.Config. This issue is mainly to track that CL during the 1.3 code freeze.

I originally proposed this at
https://groups.google.com/forum/#!topic/golang-nuts/M0LwsijM9bo; no objections were
offered.

[Brad Fitzpatrick]

Comment 1:

Labels changed: added release-go1.4, repo-main.

Status changed to Accepted.

[GopherBot]

Comment 2:

CL https://golang.org/cl/100140043 mentions this issue.

[Rob Pike]

Comment 3:

Labels changed: added release-go1.5, removed release-go1.4.

[GopherBot]

CL https://golang.org/cl/17271 mentions this issue.

[Rob Pike]

The net/rpc package is frozen, so closing this.