Keep consistent read size after closing MessageUnpacker

[okumin]

I found MessageUnpacker#getTotalReadBytes doesn't return correct size once I invoke MessageUnpacker#close.

That's because MessageUnpacker#close drops the current buffer without updating the read size
https://github.com/msgpack/msgpack-java/blob/v0.9.0/msgpack-core/src/main/java/org/msgpack/core/MessageUnpacker.java#L1738-L1740

even though MessageUnpacker#getTotalReadBytes requires the size of the latest buffer.
https://github.com/msgpack/msgpack-java/blob/v0.9.0/msgpack-core/src/main/java/org/msgpack/core/MessageUnpacker.java#L261

[komamitsu]

@xerial ^ What do you think?

[yuokada]

@komamitsu It's good to ping him via slack or twitter. IIRC, he doesn't watch notifications from github.

[xerial]

Thanks for the fix. Yeah. position value needs to be reflected to the total read size before resetting to 0