ext/flac/gstflacenc.*: Fix seeking, so that flacenc can rewrite the header with the...

ext/flac/gstflacenc.*: Fix seeking, so that flacenc can rewrite the header with the correct duration and amount of sa...

Original commit message from CVS:
* ext/flac/gstflacenc.c: (gst_flacenc_base_init),
(gst_flacenc_init), (gst_flacenc_sink_setcaps),
(gst_flacenc_seek_callback), (gst_flacenc_write_callback),
(gst_flacenc_sink_event), (gst_flacenc_chain),
(gst_flacenc_set_property), (gst_flacenc_get_property),
(gst_flacenc_change_state):
* ext/flac/gstflacenc.h:
Fix seeking, so that flacenc can rewrite the header with the
correct duration and amount of samples and all that at EOS;
also set timestamps and granulepos on outgoing buffers; add
debug category; fix state change function.