Wraps SDL_SetSurfaceBlendMode which sets the dsdl2.Surface's dsdl2.BlendMode defining blitting
dsdl2.BlendMode to set
dsdl2.SDLException if dsdl2.BlendMode unable to set
See Implementation
Wraps SDL_SetSurfaceBlendMode which sets the dsdl2.Surface's dsdl2.BlendMode defining blitting