versioner: add test output directories to gitignore.

Bug: http://b/30170081
Change-Id: Ie493d8c321bb0e8d308234dec2d42ac8306c21c6
Test: python run_tests.py
diff --git a/tools/versioner/run_tests.py b/tools/versioner/run_tests.py
index 9bac3e2..be87d6b 100755
--- a/tools/versioner/run_tests.py
+++ b/tools/versioner/run_tests.py
@@ -59,7 +59,10 @@
 
 success = True
 for test in sorted(tests):
-    if not run_test(test, os.path.join(test_dir, test)):
+    path = os.path.join(test_dir, test)
+    if not os.path.isdir(path):
+        continue
+    if not run_test(test, path):
         success = False
 
 sys.exit(0 if success else 1)