tools: Let unicode error messages through

Some toolchains (GCC) may emit error messages with unicode symbols based on
the your localization settings. Instead of being passed to the user as is,
the unicode causes an exception.

tools/make.py

@@ -19,6 +19,7 @@ limitations under the License.
 TEST BUILD & RUN
 """
 from __future__ import print_function
+from builtins import str
 import sys
 import json
 from time import sleep