This directory contains the LZ4 source from the upstream repo:
https://github.com/lz4/lz4/

Current version: 1.10.0 [ebb370ca83af193212df4dcbadcc5d87bc0de2f0]

Our in-tree copy of LZ4 does not depend on any generated files from the
upstream build system, only the lz4*.{c,h} files found in the lib
sub-directory. Therefore, it should be sufficient to simply overwrite
the in-tree files with the updated ones from upstream.

If the collection of source files changes, manual updates to moz.build may be
needed as we don't use the upstream makefiles.

Note that we do NOT use the copy of xxhash.{c,h} from the LZ4 repo. We
instead use the newer release from that project's upstream repo:
https://github.com/Cyan4973/xxHash

Current version: 0.8.3 [e626a72bc2321cd320e953a0ccf1584cad60f363]
