Comment 5 for bug 1950214

Some further research on this [1] suggests gzip may be a preferable choice on the smaller platforms (lower memory usage, and better compression anyway), plus this would alleviate the need for including lz4 in the images.

I need to do some further analysis of the decompression to see if it is still suitable there too.

[1] https://github.com/waveform80/compression/