Update to Zstandard 1.4.2
The full release notes for 1.4.1 (skipped) and 1.4.2 can be found on Github:
https://github.com/facebook/zstd/releases/tag/v1.4.1 https://github.com/facebook/zstd/releases/tag/v1.4.2
These are mostly minor updates; 1.4.1 purportedly brings something like 7%
faster decompression speed.
Relnotes: yes