librustc: Fix bug with newtype structs containing dtors

src/test/run-pass/newtype-struct-with-dtor.rs

@@ -0,0 +1,17 @@
+use core::libc::c_int;
+use core::libc;
+
+pub struct Fd(c_int);
+
+impl Drop for Fd {
+    fn finalize(&self) {
+        unsafe {
+            libc::close(**self);
+        }
+    }
+}
+
+fn main() {
+}
+
+