N3DS: Fix -Wformat warnings in tests.

All warnings were about invalid specifiers. Since U/Sint32 is a long,
using `%d` emits a -Wformat warning.

test/testautomation_guid.c

@@ -108,7 +108,7 @@ TestGuidToString(void *arg)
             /* Check bytes before guid_str_buf */
             expected_prefix = fill_char | (fill_char << 8) | (fill_char << 16) | (fill_char << 24);
             SDL_memcpy(&actual_prefix, guid_str_buf, 4);
-            SDLTest_AssertCheck(expected_prefix == actual_prefix, "String buffer memory before output untouched, expected: %i, got: %i, at size=%d", expected_prefix, actual_prefix, size);
+            SDLTest_AssertCheck(expected_prefix == actual_prefix, "String buffer memory before output untouched, expected: %" SDL_PRIu32 ", got: %" SDL_PRIu32 ", at size=%d", expected_prefix, actual_prefix, size);
 
             /* Check that we did not overwrite too much */
             written_size = 0;