First pass at changing SDL 2.0 to SDL 3.0

cmake/test/main_lib.c

@@ -17,7 +17,7 @@ int MYLIBRARY_EXPORT mylibrary_work(void);
 int mylibrary_init(void) {
     SDL_SetMainReady();
     if (SDL_Init(0) < 0) {
-        fprintf(stderr, "could not initialize sdl2: %s\n", SDL_GetError());
+        fprintf(stderr, "Could not initialize SDL: %s\n", SDL_GetError());
         return 1;
     }
     return 0;