Update zstd to version 1.4.4

[dbenamydd]

Synced with something like

git clone https://github.com/facebook/zstd.git c
cd c
git checkout v1.4.4
cd ..
git clone [email protected]:dbenamydd/zstd144.git go
find c/lib \( -name '*.h' -o -name '*.c' \) -exec cp -v {} go/ \;

[Viq111]

✅ Checked that all c and h files were from v1.4.4

Benchmark doesn't show anything too crazy on speed improv (benchmark file was the go binary created).
You can see a slight improvement on decompression speed (~2-3%) as mentioned in the release note but not the 10% announced (maybe the file is too small for it):

ᐅ benchstat ~/old ~/new
name                   old time/op    new time/op    delta
StreamCompression-4      81.5ms ± 7%    82.7ms ± 2%    ~     (p=0.136 n=9+9)
StreamDecompression-4    8.93ms ± 3%    8.63ms ± 2%  -3.40%  (p=0.000 n=10+10)
Compression-4            81.4ms ± 7%    80.9ms ± 8%    ~     (p=0.684 n=10+10)
Decompression-4          7.92ms ± 5%    7.75ms ± 2%  -2.19%  (p=0.017 n=10+9)

name                   old speed      new speed      delta
StreamCompression-4    73.2MB/s ± 7%  72.1MB/s ± 2%    ~     (p=0.136 n=9+9)
StreamDecompression-4   667MB/s ± 2%   691MB/s ± 2%  +3.52%  (p=0.000 n=10+10)
Compression-4          73.3MB/s ± 7%  73.8MB/s ± 8%    ~     (p=0.684 n=10+10)
Decompression-4         753MB/s ± 5%   769MB/s ± 2%  +2.21%  (p=0.017 n=10+9)

[Viq111]

Fixes #72