C++11: Make 'enum struct', enum-base and opaque enum decls work.

For declarations like:
enum struct Foo : long int;

Change-Id: Id813efdbc31c8d70a4b40bb0101dc33a8dd2556a
Reviewed-by: hjk <qthjk@ovi.com>

src/libs/3rdparty/cplusplus/ASTVisit.cpp

@@ -410,6 +410,7 @@ void EnumSpecifierAST::accept0(ASTVisitor *visitor)
 {
     if (visitor->visit(this)) {
         accept(name, visitor);
+        accept(type_specifier_list, visitor);
         accept(enumerator_list, visitor);
     }
     visitor->endVisit(this);