Typo feautres -> features

[kpp]

https://github.com/alexcrichton/git2-rs/blob/8002f977de375a83d134e6897b1c759f62aa3743/libgit2-sys/build.rs#L44

[alexcrichton]

Oops thanks for pointing this out! PRs are definitely more than welcome to touch up things like this :)