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/__init__.py

@@ -45,14 +45,14 @@ import os
 import re
 import sys
 
-import convert
-import jobfile
+from . import convert
+from . import jobfile
 
-from attrdict import attrdict, multiattrdict, optiondict
-from code_formatter import code_formatter
-from multidict import multidict
-from smartdict import SmartDict
-from sorteddict import SortedDict
+from .attrdict import attrdict, multiattrdict, optiondict
+from .code_formatter import code_formatter
+from .multidict import multidict
+from .smartdict import SmartDict
+from .sorteddict import SortedDict
 
 # panic() should be called when something happens that should never
 # ever happen regardless of what the user does (i.e., an acutal m5

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):

src/python/m5/util/dot_writer.py

@@ -57,6 +57,9 @@
 #
 #####################################################################
 
+from __future__ import print_function
+from __future__ import absolute_import
+
 import m5, os, re
 from m5.SimObject import isRoot, isSimObjectVector
 from m5.params import PortRef, isNullPointer

src/python/m5/util/jobfile.py

@@ -27,6 +27,7 @@
 # Authors: Nathan Binkert
 
 from __future__ import print_function
+from __future__ import absolute_import
 
 import sys
 

src/python/m5/util/pybind.py

@@ -35,6 +35,9 @@
 #
 # Authors: Andreas Sandberg
 
+from __future__ import print_function
+from __future__ import absolute_import
+
 from abc import *
 
 class PyBindExport(object):

src/python/m5/util/smartdict.py

@@ -41,9 +41,11 @@
 # rather than a normal value, and (c) coerce values written to the
 # dict to be strings.
 
+from __future__ import print_function
+from __future__ import absolute_import
 
-from convert import *
-from attrdict import attrdict
+from .convert import *
+from .attrdict import attrdict
 
 class Variable(str):
     """Intelligent proxy class for SmartDict.  Variable will use the

src/python/m5/util/sorteddict.py

@@ -25,6 +25,7 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 from __future__ import print_function
+from __future__ import absolute_import
 
 from bisect import bisect_left, bisect_right
 

src/python/m5/util/terminal.py

@@ -27,6 +27,7 @@
 # Author: Steve Reinhardt
 
 from __future__ import print_function
+from __future__ import absolute_import
 
 import sys