android: Always initialize 'log' variable

Always initialize the 'log' variable to avoid an unbound local error
when dealing with exceptions.

Review URL: https://chromiumcodereview.appspot.com/17484004

git-svn-id: http://src.chromium.org/svn/trunk/src/build@207648 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/pylib/gtest/test_package.py

@@ -144,6 +144,7 @@ class TestPackage(object):
     # to output the CRASHED marker when a crash happens.
     re_crash = re.compile('\[ CRASHED      \](.*)\r\n')
 
+    log = ''
     try:
       while True:
         full_test_name = None