Add ability to debug Go programs loaded as DLL

Hi,

I need to debug a Go application that has to reside in a DLL. In order to have the DLL loading work properly, I had to write a small C layer on top of Go.
How can I get dlv to attach to the Go code? Example code to reproduce my steps is at https://groups.google.com/d/msg/golang-nuts/ywzTYaalWLE/kn4GoobJAAAJ.

Start by reviewing the reproduction steps and example code in the linked golang-nuts discussion, then trace how Delve currently attaches to Go programs. Done means a Go program loaded as a DLL can be attached to and debugged through its Go code, with the behavior verified against that reproduction.

Written by the indexing model from the issue text.