location nodes on track.

Use last location-node for uri (maybe first would be better instead ?).

check that input_item_NewExt doesn't return NULL

should fix ticket #2353

Remark by Babal.

This is untested. Most probably nobody uses these anymore.

(but yes duplicate 2 lines of code).

Other audio codecs (cook/28_8/atrac3) will need a lot more code.