wave_imp: Treat WAVE file format as if it's QuickTime file format.

This fixes a regression introduced at ade978d, which makes
inevitable failure of wave_importer_probe() since
isom_set_media_language() requires either ISOBMFF or QTFF compatibility.
lib: Support Opus-in-ISOBMFF.

Don't distribute generated Opus-in-ISOBMFF files.
It is highly experimental stage at present.