servo: Merge #4962 - Remove the libc feature gate from cef (from Ms2ger:cef-libc); r=jdm

As it depends on the crates.io libc crate, the feature gate doesn't apply.

Source-Repo: https://github.com/servo/servo
Source-Revision: e0af48426980dd067dba00c98d6c2e9b8ebe1695

servo/ports/cef/lib.rs

@@ -7,7 +7,6 @@
 #![feature(plugin)]
 #![feature(link_args)]
 #![feature(thread_local)]
-#![feature(libc)]
 #![feature(unicode)]
 #![feature(core)]
 #![feature(std_misc)]