add patch so that libmpd can be installed

As asked by @magthe, sending a pull request. See #124.
pkg: https://www.dropbox.com/sh/vayztjixgrmt983/rhlqPJFjBN

This toolchain needs a lot more documentation to make the process easier. `makeahpkg` wasn't working for me as it could not understand commented block inside `EOF` for example. Also I had to manually specify the ghc version because otherwise it was defaulting to 7.6. 

I would really want to help improve this. Please try to add a `TODO` for example, so that people like me can help contribute.

Thanks!