Compression: fix a bug for handling of end-marker edge case
Compression: fix a bug for handling of end-marker edge case

Edge case is:

* End of input.
* Outputting extended length tokens.
* Just output a complete token, with continuation expected.

In this case, it is necessary to output an extended token with length=0,
before outputting an end marker.

cmcqueen/lzs-compression,cmcqueen/lzs-compression,cmcqueen/lzs-compression