test: Fix error messages in compile-fail tests. rs=rustbot

Author: pcwalton

src/test/compile-fail/enum-in-scope.rs

@@ -1,5 +1,5 @@
 enum hello = int;
 
 fn main() {
-    let hello = 0; //~ERROR declaration of `hello` shadows an enum that's in
-}
+    let hello = 0; //~ERROR declaration of `hello` shadows
+}

src/test/compile-fail/issue-2370-2.rs

@@ -1,9 +1,9 @@
-// error-pattern: type cat cannot be dereferenced
+// error-pattern: can only dereference structs
 struct cat {
     x: ()
 }
 
 fn main() {
     let kitty : cat = cat { x: () };
     log (error, *kitty);
-}
+}

src/test/compile-fail/issue-2370.rs

@@ -1,9 +1,9 @@
-// error-pattern: type cat cannot be dereferenced
+// error-pattern: can only dereference structs
 struct cat {
     foo: ()
 }
 
 fn main() {
     let nyan = cat { foo: () };
     log (error, *nyan);
-}
+}

src/test/compile-fail/issue-2509-a.rs

@@ -1,5 +1,5 @@
 enum foo = uint;
 
 fn main() {
-    let (foo, _) = (2, 3); //~ ERROR declaration of `foo` shadows an enum that's in scope
+    let (foo, _) = (2, 3); //~ ERROR declaration of `foo` shadows
 }