Write compilation instructions for each supported platform

[Screwtapello]

Like higan-emu/higan#39 but for bsnes

[birdybro]

Here's my notes (not yet complete) for building the linux version in WSL2 running Ubuntu 20.04. I don't know the flag for building the windows version, and I haven't tested the software I completed yet, but it might help:

How to build bsnes in Ubuntu 20.04 WSL2 (still need to figure out building windows edition of bsnes for this, but so far this does compile the linux version apparently)

sudo apt update && sudo apt full-upgrade -y

sudo apt install build-essential git automake make 
sudo apt install libgtk2.0-dev
sudo apt install libgtksourceview2.0-dev libgtksourceview2.0-0
sudo apt install libxv-dev libsdl1.2-dev libao-dev libopenal-dev g++

sudo add-apt-repository ppa:rock-core/qt4
sudo apt update
sudo apt install libqt4-dev libqt4-dev-bin

sudo apt install libsdl2-image-dev libsdl2-image-2.0-0 -y
sudo apt install libjpeg-dev libwebp-dev libtiff5-dev libsdl2-image-dev libsdl2-image-2.0-0 -y
sudo apt install libmikmod-dev libfishsound1-dev libsmpeg-dev liboggz2-dev libflac-dev libfluidsynth-dev libsdl2-mixer-dev libsdl2-mixer-2.0-0 -y

git clone https://github.com/bsnes-emu/bsnes.git
cd bsnes
cd bsnes
nice make