Simple cross compile

[dustinblackman]

Overview

Due to the Opus c library, doing cross compilation easily is well... Not easy. After various attempts of trying to modify xgo to fit my needs, I was only able to get Darwin and Linux x64 to build correctly. Also attempted to get ffmpeg to output raw opus audio but resulted in a garbled mess coming out of Discord.

https://stackoverflow.com/questions/35754212/not-outputting-opus-raw-audio
https://stackoverflow.com/questions/35759443/how-to-binary-read-an-opus-fil