Add test for Issue 2823

Author: catamorphism

src/test/compile-fail/issue-2823.rs

@@ -0,0 +1,12 @@
+struct C {
+    x: int,
+    drop {
+        #error("dropping: %?", self.x);
+    }
+}
+
+fn main() {
+    let c = C{ x: 2};
+    let d = copy c; //~ ERROR copying a noncopyable value
+    #error("%?", d.x);
+}