Function fermium::SDL_ComposeCustomBlendMode

pub unsafe extern "C" fn SDL_ComposeCustomBlendMode(
    srcColorFactor: SDL_BlendFactor, 
    dstColorFactor: SDL_BlendFactor, 
    colorOperation: SDL_BlendOperation, 
    srcAlphaFactor: SDL_BlendFactor, 
    dstAlphaFactor: SDL_BlendFactor, 
    alphaOperation: SDL_BlendOperation
) -> SDL_BlendMode