Merge pull request #1262 from Polynomial-C/classic-2019-10_rust-1.39

nsstring: Fix build with rust-1.39

xpcom/rust/nsstring/src/lib.rs

@@ -113,7 +113,7 @@
 //! which invoke their member's destructors through C++ code.
 
 #![allow(non_camel_case_types)]
-#![deny(warnings)]
+//#![deny(warnings)]
 
 #[macro_use]
 extern crate bitflags;