* guix/lzlib.scm (%compression-levels): Splice the rest of each element.
(dictionary-size+match-length-limit): New procedure.
(make-lzip-output-port, make-lzip-input-port/compressed): Use it.
* tests/lzlib.scm ("Bytevector of size relative to Lzip internal buffers (2 * dictionary)"):
Use 'dictionary-size+match-length-limit' instead of 'assoc-ref'.