Emscripten: use UTF8ToString instead of Pointer_stringify

src/SDL_assert.c

@@ -250,7 +250,7 @@ SDL_PromptAssertion(const SDL_assert_data *data, void *userdata)
             SDL_bool okay = SDL_TRUE;
             char *buf = (char *) EM_ASM_INT({
                 var str =
-                    Pointer_stringify($0) + '\n\n' +
+                    UTF8ToString($0) + '\n\n' +
                     'Abort/Retry/Ignore/AlwaysIgnore? [ariA] :';
                 var reply = window.prompt(str, "i");
                 if (reply === null) {