add some rough notes on compiling for windows with msys2
add some rough notes on compiling for windows with msys2

Agadoul/DevIL,Agadoul/DevIL,bcampbell/DevIL,DentonW/DevIL,bcampbell/DevIL,DentonW/DevIL,Agadoul/DevIL,Agadoul/DevIL,DentonW/DevIL,bcampbell/DevIL,DentonW/DevIL,DentonW/DevIL,Agadoul/DevIL,DentonW/DevIL,Agadoul/DevIL,bcampbell/DevIL,bcampbell/DevIL,bcampbell/DevIL