The current logic inadvertently defines SDL_VIDEO_RENDER_SW as 0 when it is not explicitly defined, which still allows it to be treated as defined during #ifdef SDL_VIDEO_RENDER_SW checks. This seems to undermine the intended behavior of SDL_LEAN_AND_MEAN by always including the software renderer, even when explicitly excluded.
#ifndef SDL_VIDEO_RENDER_SW
#define SDL_VIDEO_RENDER_SW !SDL_LEAN_AND_MEAN
#endif