store the normalized types of statics in MIR Lvalues

The types of statics, like all other items, are stored in the tcx
unnormalized. This is necessarily so, because
    a) Item types other than statics have generics, which can't be
normalized.
    b) Eager normalization causes undesirable on-demand dependencies.

Keeping with the principle that MIR lvalues require no normalization in
order to interpret, this patch stores the normalized type of the statics
in the Lvalue and reads it to get the lvalue type.

Fixes #39367.

src/test/run-pass/issue-39367.rs

@@ -0,0 +1,49 @@
+// Copyright 2017 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.
+
+use std::ops::Deref;
+
+struct ArenaSet<U: Deref, V=<U as Deref>::Target>(U, &'static V)
+    where V: 'static + ?Sized;
+
+static Z: [u8; 4] = [1,2,3,4];
+
+fn arena() -> &'static ArenaSet<Vec<u8>> {
+    fn __static_ref_initialize() -> ArenaSet<Vec<u8>> {
+        ArenaSet(vec![], &Z)
+    }
+    unsafe {
+        use std::sync::{Once, ONCE_INIT};
+        fn require_sync<T: Sync>(_: &T) { }
+        unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
+            use std::mem::transmute;
+            use std::boxed::Box;
+            static mut DATA: *const ArenaSet<Vec<u8>> = 0 as *const ArenaSet<Vec<u8>>;
+
+            static mut ONCE: Once = ONCE_INIT;
+            ONCE.call_once(|| {
+                DATA = transmute
+                    ::<Box<ArenaSet<Vec<u8>>>, *const ArenaSet<Vec<u8>>>
+                    (Box::new(__static_ref_initialize()));
+            });
+
+            &*DATA
+        }
+        let static_ref = __stability();
+        require_sync(static_ref);
+        static_ref
+    }
+}
+
+fn main() {
+    let &ArenaSet(ref u, v) = arena();
+    assert!(u.is_empty());
+    assert_eq!(v, Z);
+}