ART: Add simple failure list to tail of testrunner output

After repeating the output of failed tests, print the sorted list
of failed test configurations. The list is separated from the full
output by a separator line.

Bug: 37116837
Test: m test-art-host
Test: manually fail test
Change-Id: I2a206fba47db2626d390bb60c70b843f56a1b987
diff --git a/test/testrunner/testrunner.py b/test/testrunner/testrunner.py
index c99159f..77ef25a 100755
--- a/test/testrunner/testrunner.py
+++ b/test/testrunner/testrunner.py
@@ -750,6 +750,9 @@
     print_text(COLOR_ERROR + 'FAILED: ' + COLOR_NORMAL + '\n')
     for test_info in failed_tests:
       print_text(('%s\n%s\n' % (test_info[0], test_info[1])))
+    print_text(COLOR_ERROR + '----------' + COLOR_NORMAL + '\n')
+    for failed_test in sorted([test_info[0] for test_info in failed_tests]):
+      print_text(('%s\n' % (failed_test)))
 
 
 def parse_test_name(test_name):