Merge pull request ARMmbed#9964 from bridadan/fix_references_to_basestring

Add imports of basestring for python 3

Author: Cruz Monrreal II

tools/build_release.py

@@ -21,6 +21,7 @@
 from optparse import OptionParser
 import json
 from shutil import copy
+from past.builtins import basestring
 
 # Be sure that the tools directory is in the search path
 ROOT = abspath(join(dirname(__file__), ".."))

tools/export/__init__.py

@@ -24,6 +24,7 @@
 import copy
 from shutil import rmtree, copyfile
 import zipfile
+from past.builtins import basestring
 
 from ..resources import Resources, FileType, FileRef
 from ..config import ALLOWED_FEATURES

tools/targets/lint.py

@@ -29,6 +29,7 @@
 from copy import copy
 from yaml import dump_all
 import argparse
+from past.builtins import basestring
 
 from tools.targets import Target, set_targets_json_location, TARGET_MAP
 
@@ -274,4 +275,3 @@ def main():
 
 if __name__ == "__main__":
     sys.exit(main())
-