Bypass Python exmples not supported by -builtin

Builtin classes as exceptions not supported, so don't run these aspects
of the examples when using -builtin.

Examples/python/exception/example.i

@@ -10,3 +10,12 @@
 /* Let's just grab the original header file here */
 %include "example.h"
 
+%inline %{
+// The -builtin SWIG option results in SWIGPYTHON_BUILTIN being defined
+#ifdef SWIGPYTHON_BUILTIN
+bool is_python_builtin() { return true; }
+#else
+bool is_python_builtin() { return false; }
+#endif
+%}
+