test: fix test-sync-io-option
test: fix test-sync-io-option

This test was failing occasionally both locally and on CI. Switched
from using spawn to execFile for a more reliable test.

Fixes: https://github.com/nodejs/io.js/issues/1837
PR-URL: https://github.com/nodejs/io.js/pull/1840
Reviewed-By: Roman Reiss <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@silverwind.io>
Reviewed-By: Trevor Norris <9cb5491eb5770dd8e0bf77a8a0335abf5f0488c5@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node