Fixes for API changes in core.

Fixes for API changes in core.

Original commit message from CVS:
* ext/ogg/gstoggmux.c: (gst_ogg_mux_get_headers),
(gst_ogg_mux_set_header_on_caps):
* ext/theora/theoraenc.c: (theora_set_header_on_caps):
* ext/vorbis/vorbisenc.c: (gst_vorbisenc_set_header_on_caps):
* ext/vorbis/vorbisparse.c: (vorbis_parse_set_header_on_caps):
* gst-libs/gst/audio/multichannel.c:
(gst_audio_set_channel_positions),
(gst_audio_set_structure_channel_positions_list):
* gst/playback/gstdecodebin.c: (dynamic_create):
* gst/playback/gstplaybasebin.c: (setup_source), (mute_group_type):
* gst/playback/gststreaminfo.c: (gst_stream_info_set_mute):
Fixes for API changes in core.