Fix fallout in tests.

src/test/compile-fail/gated-non-ascii-idents.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern crate bäz; //~ ERROR non-ascii idents
+extern crate core as bäz; //~ ERROR non-ascii idents
 
 use föö::bar; //~ ERROR non-ascii idents
 

src/test/compile-fail/self_type_keyword.rs

@@ -39,11 +39,17 @@ pub fn main() {
     }
 }
 
-use std::option::Option as Self;
-//~^ ERROR expected identifier, found keyword `Self`
+mod m1 {
+    extern crate core as Self;
+    //~^ ERROR expected identifier, found keyword `Self`
+}
 
-extern crate Self;
-//~^ ERROR expected identifier, found keyword `Self`
+mod m2 {
+    use std::option::Option as Self;
+    //~^ ERROR expected identifier, found keyword `Self`
+}
 
-trait Self {}
-//~^ ERROR expected identifier, found keyword `Self`
+mod m3 {
+    trait Self {}
+    //~^ ERROR expected identifier, found keyword `Self`
+}