Not initialising granulepos leads to it having arbitrary values in the
encoded stream including possibly negative values which are not valid
and confuse opusdec. Explicitly initialise opus_encoder::granulepos
to avoid that problem.
The "written" argument to shine_encode_buffer() and shine_flush() was
changed from "long" to "int", which breaks API and ABI compatibility.
This is a big deal, and it doesn't seem worthwile to keep support for
the (broken) 3.0 release.
