Removed SDL_LOADSO_DISABLED

Loading shared libraries is core functionality on platforms that support it.

src/loadso/dummy/SDL_sysloadso.c

@@ -20,7 +20,7 @@
 */
 #include "SDL_internal.h"
 
-#if defined(SDL_LOADSO_DUMMY) || defined(SDL_LOADSO_DISABLED)
+#if defined(SDL_LOADSO_DUMMY)
 
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 /* System dependent library loading routines                           */
@@ -44,4 +44,4 @@ void SDL_UnloadObject(void *handle)
     /* no-op. */
 }
 
-#endif /* SDL_LOADSO_DUMMY || SDL_LOADSO_DISABLED */
+#endif /* SDL_LOADSO_DUMMY */