releasetools: Log to stdout when running tests.

This sets up the root logger while running tests. It also logs to
stdout, as our Python test result parser doesn't like outputs from
stderr.

Test: `python -m unittest discover build/make/tools/releasetools \
          > /dev/null` doesn't print log lines.
Change-Id: Ic99711bd458bc4b67b38226786fed604c2168476

tools/releasetools/test_utils.py

@@ -18,13 +18,18 @@
 Utils for running unittests.
 """
 
+import logging
 import os
 import os.path
 import struct
+import sys
 import unittest
 
 import common
 
+# Some test runner doesn't like outputs from stderr.
+logging.basicConfig(stream=sys.stdout)
+
 
 def get_testdata_dir():
   """Returns the testdata dir, in relative to the script dir."""