Revert "rustc_trans: don't apply noalias on returned references."

This reverts commit 9b2878c.

Author: arielb1

src/librustc_trans/abi.rs

@@ -792,8 +792,7 @@ impl<'a, 'tcx> FnType<'tcx> {
                     // dependencies rather than pointer equality
                     let no_alias = match kind {
                         PointerKind::Shared => false,
-                        PointerKind::UniqueOwned => true,
-                        PointerKind::Frozen |
+                        PointerKind::Frozen | PointerKind::UniqueOwned => true,
                         PointerKind::UniqueBorrowed => !is_return
                     };
                     if no_alias {