ext/flac/gstflacdec.*: Rewrite flacdec a bit, so that even seeking might work now. Most importantly, don't act upon a...

Original commit message from CVS:
* ext/flac/gstflacdec.c: (gst_flac_dec_base_init),
(gst_flac_dec_class_init), (gst_flac_dec_init),
(gst_flac_dec_metadata_callback), (gst_flac_dec_error_callback),
(gst_flac_dec_eof), (gst_flac_dec_write), (gst_flac_dec_loop),
(gst_flac_dec_convert_src), (gst_flac_dec_get_src_query_types),
(gst_flac_dec_src_query), (gst_flac_dec_send_newsegment),
(gst_flac_dec_handle_seek_event), (gst_flac_dec_src_event),
(gst_flac_dec_change_state):
* ext/flac/gstflacdec.h:
Rewrite flacdec a bit, so that even seeking might work now. Most
importantly, don't act upon any flow return values we get, just tell
the decoder everything's dandy and act on the flow return values
later on in the loop function. We don't want to mess up the internal
decoder state for non-fatal things like flushing pads etc. Other
than that, use GstSegment (segment seeks don't work yet though, but
should be easy to add), use boilerplate macros, drop the superfluous
'flacdec:' from debug messages, use gst_util_uint64_scale_int, and
lots of other things.