clippy 0.0.170

A bunch of helpful lints to avoid common pitfalls in Rust
use std::env;

fn main() {
    // Forward the profile to the main compilation
    println!("cargo:rustc-env=PROFILE={}", env::var("PROFILE").unwrap());
    // Don't rebuild even if nothing changed
    println!("cargo:rerun-if-changed=build.rs");
}