Add 12 num::NonZero* types for each primitive integer

RFC: https://github.com/rust-lang/rfcs/pull/2307

src/libstd/lib.rs

@@ -282,6 +282,7 @@
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
 #![feature(exhaustive_patterns)]
+#![feature(nonzero)]
 #![feature(num_bits_bytes)]
 #![feature(old_wrapping)]
 #![feature(on_unimplemented)]