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/util/code_formatter.py

@@ -279,7 +279,7 @@ class code_formatter(object):
 __all__ = [ "code_formatter" ]
 
 if __name__ == '__main__':
-    from code_formatter import code_formatter
+    from .code_formatter import code_formatter
     f = code_formatter()
 
     class Foo(dict):