[OCaml] Runtime tests for fvirtual, overload_polymorphic and some others

Add runtime tests for conversion, extend_typedef_class,
extend_constructor_destructor, fvirtual, overload_polymorphic,
template_rename, and using1.

Examples/test-suite/ocaml/extend_constructor_destructor_runme.ml

@@ -0,0 +1,12 @@
+open Swig
+open Extend_constructor_destructor
+
+let check o v =
+  assert ((o -> "[ivar]" () as int) = v);
+  ignore (o -> "~" ());
+  assert ((_globalVar '() as int) = -v)
+
+let ctors = [new_AStruct; new_BStruct; new_CStruct; new_DStruct; new_EStruct;
+             new_FStruct; new_GStruct]
+
+let _  = List.iteri (fun i c -> let j = succ i in check (c (C_int j)) j) ctors