Use faster gzip package

[klauspost]

Before:

BenchmarkCompression/gzip/compress-32                 81          13573535 ns/op           8.77 MB/s       10115 B/op          1 allocs/op
BenchmarkCompression/gzip/decompress-32              580           2023225 ns/op         959.10 MB/s        7563 B/op         53 allocs/op

  gzip:         93.86%

After:

BenchmarkCompression/gzip/compress-32                224           5340019 ns/op          24.42 MB/s        4838 B/op          1 allocs/op
BenchmarkCompression/gzip/decompress-32              692           1713771 ns/op        1132.28 MB/s         566 B/op         34 allocs/op

  gzip:         93.28%

Pretty typical scenario for default settings, 2x faster, sometimes at a slight compression loss. This provides a much better "default" trade-off than the stdlib.

For people regretting the 0.6% loss the higher compression levels can be used.

Edit: Next release will bring compression to 93.43% due to klauspost/compress#656

Decompression typically has even bigger margin, but it depends on the input.

It also provides much better handling of incompressible data:

BenchmarkCompression/gzip/compress-32                 36          31021311 ns/op          62.57 MB/s       22738 B/op          1 allocs/op
-> 
BenchmarkCompression/gzip/compress-32               3555            311620 ns/op        6227.58 MB/s          17 B/op          1 allocs/op

[dominicbarnes]

@klauspost it looks like CircleCI had some sort of trouble executing the run. Oddly enough, we can't seem to get any of the UI to work for this build, would you mind throwing on an empty commit or something to try and trigger once again?

[klauspost]

@dominicbarnes Tried an innocent change. Same result. Seems like a permission issue and you need to approve me.

[achille-roussel]

I don't understand why CircleCI is bugging us on this PR (and don't have time to waste to figure it out), it runs fine for other external contributors.

I ran the tests locally and everything is looking good, let's get this merged 👍

Thanks for your contribution @klauspost !