python: Enforce absolute imports for Python 3 compatibility

Change-Id: Ia88d7fd472f7aed9b97df81468211384981bf6c6
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/15983
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/python/m5/SimObject.py

@@ -44,6 +44,7 @@
 #          Andreas Sandberg
 
 from __future__ import print_function
+from __future__ import absolute_import
 
 import sys
 from types import FunctionType, MethodType, ModuleType