update c source to 0.8.2

[chris-ha458]

you can leave out the optimization commits if it is deemed unnecessary

[DoumanAsh]

I will check it later this day and maybe make commit myself if necessary

[DoumanAsh]

@chris-ha458 Here is commit https://github.com/DoumanAsh/xxhash-c-sys/commit/34a43c648762230b26b582a3a105829ac3f2b173#diff-2e9d962a08321605940b5a657135052fbcef87b5e360662bb527c96d9a615542

I will publish it soon

[DoumanAsh]

Regarding optimizations: they are always should be inherited from user environment Setting optimizations in your Cargo.toml/build.rs only useful for binaries