Playback of chained Opus files is unsupported

Sample: https://jmvalin.ca/misc_stuff/chain_works.opus

Expected result (generated with opusdec from https://git.xiph.org/?p=opus-tools.git):

http://people.videolan.org/~tmatth/chain_works.wav

My guess is that this is an ogg demuxer limitation but the Opus decoder may need to be adapted as well.

See also: https://bugzilla.gnome.org/show_bug.cgi?id=782132