Setup environment for static compilation of libgit

I would like to leverage libgit to allow for compilation with native git bindings using [git2go](https://github.com/libgit2/git2go). This has the unfortunate complication of requiring CGO multi platform compilation of libgit.

I'm hoping [xgo](https://github.com/karalabe/xgo) will make this process much easier and enable multiplatform compilation on Linux.
