ext/amrwb/: Add newsegment and discont handling. Some code cleanups. Don't leak the...

ext/amrwb/: Add newsegment and discont handling. Some code cleanups. Don't leak the adapter, unref it in a new finali...

Original commit message from CVS:
* ext/amrwb/gstamrwbdec.c: (gst_amrwbdec_base_init),
(gst_amrwbdec_class_init), (gst_amrwbdec_finalize),
(gst_amrwbdec_event), (gst_amrwbdec_chain),
(gst_amrwbdec_state_change):
* ext/amrwb/gstamrwbdec.h:
* ext/amrwb/gstamrwbparse.c: (gst_amrwbparse_base_init),
(gst_amrwbparse_pull_header), (gst_amrwbparse_loop):
Add newsegment and discont handling. Some code cleanups. Don't leak
the adapter, unref it in a new finalize method instead. Sync the
parser with the amr-nb changes.