Add "Failing Tests .." line to dosep logs

[chying]

Summary

-Buildbot parser depends on this line as start flag
-Will remove the dependency from buildbot parser, but it takes some time to take effect
-Will remove this line from printout after buildbot master reconfig

test/dosep.py

for xtime in expected_timeout:
         if result:
             test_name = os.path.splitext(xtime)[0]
             touch(os.path.join(session_dir, "{}-{}".format(result, test_name)))
 
     print "Ran %d test suites (%d failed) (%f%%)" % (num_test_files, len(failed), 100.0*len(failed)/num_test_files)
     print "Ran %d test cases (%d failed) (%f%%)" % (num_tests, all_fails, 100.0*all_fails/num_tests)
     if len(failed) > 0:
         failed.sort()
+        print "Failing Tests (%d)" % len(failed)
         for f in failed:
             print "%s: LLDB (suite) :: %s (%s)" % (
                 "TIMEOUT" if f in timed_out else "FAIL", f, system_info
             )
         sys.exit(1)
     sys.exit(0)
 
 if __name__ == '__main__':
     main()