Use wrappers in the nonzero crate so users don’t need unstable features

components/remutex/Cargo.toml

@@ -9,9 +9,6 @@ publish = false
 name = "servo_remutex"
 path = "lib.rs"
 
-[features]
-unstable = ["nonzero/unstable"]
-
 [dependencies]
 lazy_static = "0.2"
 log = "0.3.5"

components/remutex/lib.rs

@@ -10,8 +10,6 @@
 //! It provides the same interface as https://github.com/rust-lang/rust/blob/master/src/libstd/sys/common/remutex.rs
 //! so if those types are ever exported, we should be able to replace this implemtation.
 
-#![cfg_attr(feature = "unstable", feature(nonzero))]
-
 extern crate nonzero;
 #[macro_use] extern crate lazy_static;
 #[macro_use] extern crate log;