ext/jpeg/: Refuse sink caps in the encoder if width or height is not a multiple of 16, the encoder does not support t...

Original commit message from CVS:
* ext/jpeg/gstsmokedec.c: (gst_smokedec_chain):
* ext/jpeg/gstsmokeenc.c: (gst_smokeenc_setcaps),
(gst_smokeenc_resync), (gst_smokeenc_chain):
Refuse sink caps in the encoder if width or height is not a
multiple of 16, the encoder does not support that yet; along the
same lines, check the return value of the encoder setup function;
also remove some debug log clutter.