Don't assert on API parameters

This causes lots of spam in test automation and it's not clear it's useful to developers. If we need this level of validation, we should add a log category for it.

src/render/SDL_render.c

@@ -47,14 +47,12 @@ this should probably be removed at some point in the future.  --ryan. */
 #define SDL_WINDOWRENDERDATA    "_SDL_WindowRenderData"
 
 #define CHECK_RENDERER_MAGIC(renderer, retval) \
-    SDL_assert(renderer && renderer->magic == &renderer_magic); \
     if (!renderer || renderer->magic != &renderer_magic) { \
         SDL_SetError("Invalid renderer"); \
         return retval; \
     }
 
 #define CHECK_TEXTURE_MAGIC(texture, retval) \
-    SDL_assert(texture && texture->magic == &texture_magic); \
     if (!texture || texture->magic != &texture_magic) { \
         SDL_SetError("Invalid texture"); \
         return retval; \