Add compression format options - lz4 for sure, maybe xz

Spectrum Scale 4.2 added support for zlib compression. zlib is moderate compression, and low-medium speed. The implementation allows for compression as a foreground command, or background action. Either is likely to be slow. Decompression can be done in the foreground or background to convert to a decompressed file, or client reads are decompressed (relatively slowly) in-line by clients.

I would suggest the following additional options. [These can be implemented cross-platform, my personal priority would only be for x86_64 linux)]
1. Add support for lz4 (-9). It is a incredibly lightweight/fast algorithm which could in some cases actually speed access by requiring the transfer of less data... ref: https://cyan4973.github.io/lz4/#lz4usedby . It is used by zfs and has native support in the linux kernel.
This should be the default compression format for SS IMHO...

2. Add support (as an option) to support xz as the cold archive format. It is typically slower and tighter compression than zlib. If someone has compressible cold data, this should be a better size than zlib most of the time...

3a. Add an option to trial compression format on a file... If the file is smaller than ~4MB, compress with the configured default (again, I'd suggest lz4)... Larger than 4MB, compress the first 25% of the file or 32MB (whichever is less) into each compression algorithm, see which yielded the the smallest result OR was within 10% of the next largest size while being > 25% faster (this could also be used to end the test early if the size/time would prevent the slower option 'winning', which includes the uncompressed original among the options...