Code review comment for lp:~sergei.glushchenko/percona-xtrabackup/20-decompress

After further analysis and discussions it was decided that this feature does not really have real applications, while complicating the xbstream architecture significantly.

Users willing to utilize compression only to speed up transferring the entire archive to another host do not really need built-in compression in XtraBackup. That feature was implemented for different use cases. Instead, users can use normal uncompressed stream in XtraBackup (either tar, or xbstream in case of parallel or incremental backups) and then use external compression utilities (either single- or multi-threaded) to compress the stream and decompress it on remote host.