BaseTools: Use absolute import in AutoGen

Based on "futurize -f libfuturize.fixes.fix_absolute_import

Contributed-under: TianoCore Contribution Agreement 1.1
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

BaseTools/Source/Python/AutoGen/GenMake.py

@@ -13,6 +13,7 @@
 
 ## Import Modules
 #
+from __future__ import absolute_import
 import Common.LongFilePathOs as os
 import sys
 import string
@@ -23,7 +24,7 @@ from Common.MultipleWorkspace import MultipleWorkspace as mws
 from Common.BuildToolError import *
 from Common.Misc import *
 from Common.StringUtils import *
-from BuildEngine import *
+from .BuildEngine import *
 import Common.GlobalData as GlobalData
 from collections import OrderedDict