Make is_native_object into a debug builtin

Author: msimacek

graalpython/com.oracle.graal.python.test/src/tests/cpyext/__init__.py

@@ -59,7 +59,9 @@ def assert_raises(err, fn, *args, **kwargs):
 
 
 if sys.implementation.name == 'graalpy':
-    is_native_object = __graalpython__.is_native_object
+    is_native_object = getattr(__graalpython__, 'is_native_object', None)
+    if not is_native_object:
+        raise RuntimeError("Needs to be run with --python.EnableDebuggingBuiltins")
 else:
     def is_native_object(obj):
         return True

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/GraalPythonModuleBuiltins.java

@@ -248,6 +248,7 @@ public void postInitialize(Python3Core core) {
             mod.setAttribute(tsLiteral("tdebug"), PNone.NO_VALUE);
             mod.setAttribute(tsLiteral("set_storage_strategy"), PNone.NO_VALUE);
             mod.setAttribute(tsLiteral("dump_heap"), PNone.NO_VALUE);
+            mod.setAttribute(tsLiteral("is_native_object"), PNone.NO_VALUE);
         }
     }