Set the exit code in `tools/test.py` to indicate success or failure.

Change-Id: If7ad98423ed2a58ad201c7c71c93b95781739e5a
diff --git a/tools/test.py b/tools/test.py
index b89ac08..1b344ca 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -427,3 +427,5 @@
         rc |= RunBenchmarks()
 
   PrintStatus(rc == 0)
+
+  sys.exit(rc)