Fixed a comment to C89 style as of…

Fixed a comment to C89 style as of http://drj11.wordpress.com/2008/10/02/python-and-bragging-about-c89/

Objects/frameobject.c

@@ -517,7 +517,7 @@ frame_sizeof(PyFrameObject *f)
 	nfrees = PyTuple_GET_SIZE(f->f_code->co_freevars);
 	extras = f->f_code->co_stacksize + f->f_code->co_nlocals +
 		 ncells + nfrees;
-	// subtract one as it is already included in PyFrameObject
+	/* subtract one as it is already included in PyFrameObject */
 	res = sizeof(PyFrameObject) + (extras-1) * sizeof(PyObject *);
 
 	return PyInt_FromSsize_t(res);