Consider using `cfg-if` crate

[Trangar]

Hello,

While reading through the code I noticed all the #[cfg(...)] statements, and I was wondering if you knew cfg-if existed? https://github.com/alexcrichton/cfg-if

This could help clean up the code and make sure that only 1 fn ever gets compiled in the code.

I'd be willing to implement this.

[Andrew Gallant]

I was using cfg-if. I ripped it out very recently. Look at the recent commits.

[Trangar]

Related commit for people that might wonder about this in the future: a579796