setTrack()/setYear() accepts 0 to remove the tag as per documentation/functionality across other tpyes (mp3/flac/...); m4a do not honour this and instead sets the underlying value to 0.
setTrack()/setYear() accepts 0 to remove the tag as per
documentation/functionality across other tpyes (mp3/flac/...); m4a do not honour
this and instead sets the underlying value to 0.

This commit fixes this issue (#911)

taglib/taglib,taglib/taglib,taglib/taglib