[OCaml] Runtime tests for template_opaque, using_extend and some others

Add runtime tests for namespace_virtual_method, template_opaque,
using_extend, using_inherit, using_pointers, using_private, and
varargs_overload.

Examples/test-suite/ocaml/varargs_overload_runme.ml

@@ -0,0 +1,15 @@
+open Swig
+open Varargs_overload
+
+let _ =
+  assert (_vararg_over1 '("Hello") as string = "Hello");
+  assert (_vararg_over1 '(2) as string = "2");
+  assert (_vararg_over2 '("Hello") as string = "Hello");
+  assert (_vararg_over2 '(2, 2.2) as string = "2 2.2");
+
+  assert (_vararg_over3 '("Hello") as string = "Hello");
+  assert (_vararg_over3 '(2, 2.2, "hey") as string = "2 2.2 hey");
+  assert (_vararg_over4 '("Hello") as string = "Hello");
+  assert (_vararg_over4 '(123) as string = "123");
+  assert (_vararg_over4 '("Hello", 123) as string = "Hello")
+;;