https://jira.mongodb.org/browse/SERVER-43710 upgraded Zstd to 1.4.3.

Currently Mongodb 4.2.8 runs Zstd 1.3.7. 

In 1.3.8 (https://github.com/facebook/zstd/releases/tag/v1.3.8) - performance improvement

In 1.4.0 (https://github.com/facebook/zstd/releases/tag/v1.4.0) - 6-8% compression performance improvement for zstd level 1

In 1.4.1 (https://github.com/facebook/zstd/releases/tag/v1.4.1) - ~ 5-10% improvement for decompression speed 

In 1.4.4 (https://github.com/facebook/zstd/releases/tag/v1.4.4) - another 10 % improvement for decompression speed

Would love to take advantage of these improvement while maintaining mongodb version 4.2.X!

Thanks

Oliver