test: fix flaky test-benchmark-events

Make sure each benchmark file only runs one combination of options.
Allow for zero iterations for short benchmark.

Author: Trott

test/parallel/test-benchmark-events.js

@@ -4,4 +4,6 @@ require('../common');
 
 const runBenchmark = require('../common/benchmark');
 
-runBenchmark('events', ['n=1']);
+runBenchmark('events',
+             ['argc=0', 'listeners=1', 'n=1'],
+             { NODEJS_BENCHMARK_ZERO_ALLOWED: 1 });