Adds bench expectations to expectations/bench; fixes bench alert test's dependency on script line n…

bench/check_bench_regressions.py

Index: bench/check_bench_regressions.py
diff --git a/bench/check_bench_regressions.py b/bench/check_bench_regressions.py
index 8f648dc2b0f23cdbb05b721619c10163af8e96d4..86ead549579eb49de9d2b4ecc094769d34d8ca74 100644
--- a/bench/check_bench_regressions.py
+++ b/bench/check_bench_regressions.py
@@ -175,7 +175,11 @@ def check_expectations(lines, expectations, key_suffix):
           outputs.extend(['', header] + li)
 
     if outputs:
-        raise Exception('\n'.join(outputs))
+        # Directly raising Exception will have stderr outputs tied to the line
+        # number of the script, so use sys.stderr.write() instead.
+        # Add a trailing newline to supress new line checking errors.
+        sys.stderr.write('\n'.join(['Exception:'] + outputs + ['\n']))
+        exit(1)
 
 
 def main():