Change the trivial cast lints to allow by default

src/librustc/lib.rs

@@ -48,7 +48,6 @@
 #![cfg_attr(test, feature(test))]
 
 #![allow(trivial_casts)]
-#![allow(trivial_numeric_casts)]
 
 extern crate arena;
 extern crate flate;

src/librustc/lint/builtin.rs

@@ -102,13 +102,13 @@ declare_lint! {
 
 declare_lint! {
     pub TRIVIAL_CASTS,
-    Warn,
+    Allow,
     "detects trivial casts which could be removed"
 }
 
 declare_lint! {
     pub TRIVIAL_NUMERIC_CASTS,
-    Warn,
+    Allow,
     "detects trivial casts of numeric types which could be removed"
 }
 /// Does nothing as a lint pass, but registers some `Lint`s