[OCaml] Runtime tests for constructor_rename, cpp_nodefault and some others

Add runtime tests for constructor_rename, cpp_nodefault, extend,
extend_special_variables, extend_template, extern_c, and
global_ns_arg.

Examples/test-suite/ocaml/extend_runme.ml

@@ -0,0 +1,26 @@
+open Swig
+open Extend
+
+let _ =
+  let base1 = new_Base '() and base2 = new_Base '(10) in
+  assert ((base1 -> "[value]" () as int) = 0);
+  assert ((base2 -> "[value]" () as int) = 10);
+  let cint = C_int 5 in
+  assert ((base1 -> "method" (cint) as int) = 5);
+  assert ((_Base_zeroVal '() as int) = 0);
+  assert ((base2 -> "currentValue" () as int) = 10);
+  let cint = C_int 7 in
+  assert ((base2 -> "extendmethod" (cint) as int) = 14);
+;;
+
+let _ =
+  let der1 = new_Derived '(0) and der2 = new_Derived '(17) in
+  assert ((der1 -> "[value]" () as int) = 0);
+  let cint = C_int 5 in
+  assert ((der1 -> "method" (cint) as int) = 10);
+  assert ((der2 -> "[value]" () as int) = 34);
+  let cfloat = C_float 200. in
+  ignore (der2 -> "[extendval]" (cfloat));
+  assert (abs_float ((der2 -> "[actualval]" () as float) -. 2.) < 0.001);
+  assert (abs_float ((der2 -> "[extendval]" () as float) -. 200.) < 0.001);
+;;