Regression tests for passing enum-typed consts by reference.

If the PointerCast in trans_def_lvalue is removed, these cases cause
LLVM assertion failures.

src/test/run-pass/const-enum-byref-self.rs

@@ -0,0 +1,25 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+enum E { V, VV(int) }
+const C: E = V;
+
+impl E {
+    fn method(&self) {
+        match *self {
+            V => {}
+            VV(*) => fail
+        }
+    }
+}
+
+fn main() {
+    C.method()
+}

src/test/run-pass/const-enum-byref.rs

@@ -0,0 +1,23 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+enum E { V, VV(int) }
+const C: E = V;
+
+fn f(a: &E) {
+    match *a {
+        V => {}
+        VV(*) => fail
+    }
+}
+
+fn main() {
+    f(&C)
+}