So https://http2.golang.org/reqinfo has a RemoteAddr of the client's
actual IP address.

Change-Id: I9db52b2f451ad937d013dd78078e4228e732ffe0
Reviewed-on: https://go-review.googlesource.com/99235Reviewed-by: David Anderson <danderson@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>