Remove obsolete Python 2 comment

I found a comment that referred to Python 2, but that is now obsolete
-- the code it refers to is gone.  I'm checking in this patch to
remove the comment.

There's a similar comment elsewhere, but I plan to remove that one in
another patch I'm going to submit shortly.

gdb/python/py-value.c

@@ -1840,13 +1840,6 @@ convert_value_from_python (PyObject *obj)
 	  if (cmp >= 0)
 	    value = value_from_longest (builtin_type_pybool, cmp);
 	}
-      /* Make a long logic check first.  In Python 3.x, internally,
-	 all integers are represented as longs.  In Python 2.x, there
-	 is still a differentiation internally between a PyInt and a
-	 PyLong.  Explicitly do this long check conversion first. In
-	 GDB, for Python 3.x, we #ifdef PyInt = PyLong.  This check has
-	 to be done first to ensure we do not lose information in the
-	 conversion process.  */
       else if (PyLong_Check (obj))
 	{
 	  LONGEST l = PyLong_AsLongLong (obj);