Workaround for clang 3.2 libc++ empty struct bug.

Certain tests have empty structs or classes.
This encounters a bug with clang: http://llvm.org/bugs/show_bug.cgi?id=16764
This is fixed in later versions of clang, but not the version
currently bundled with Mavericks and XCode 5

Examples/test-suite/std_containers.i

@@ -191,7 +191,8 @@ template <class C> struct Param
 
   struct Foo
   {
-    Foo(int i) {
+    int x;
+    Foo(int i) : x(i) {
     }
   };