ext/speex/gstspeexdec.c: Correctly take the granulepos from upstream if possible...

ext/speex/gstspeexdec.c: Correctly take the granulepos from upstream if possible and correctly handle the granulepos ...

Original commit message from CVS:
* ext/speex/gstspeexdec.c: (speex_dec_chain_parse_data):
Correctly take the granulepos from upstream if possible and
correctly handle the granulepos in various calculations: the
granulepos is the sample number of the _last_ sample in a frame, not
the first.
* ext/speex/gstspeexenc.c: (gst_speex_enc_sinkevent),
(gst_speex_enc_encode), (gst_speex_enc_chain),
(gst_speex_enc_change_state):
* ext/speex/gstspeexenc.h:
Handle non-zero start timestamps in the encoder and detect/handle
stream discontinuities. Fixes bug #547075.