Log Message:
Update archivers/lz4 to 1.7.5.

- lz4hc : new high compression mode : levels 10-12 compress more and slower
- lz4cat : fix : works with relative path (#284) and stdin (#285)
- cli : fix minor notification when using -r recursive mode
- API : lz4frame : LZ4F_frameBound(0) gives upper bound of *flush() and *End() \ 
operations
- doc : markdown version of man page
- build : Makefile : fix make -jX lib+exe concurrency
- build : cmake : improvements by Michal Gorny