test-child-process-pass-fd.js parent can exit with an error on failure
to fork, in which case it will leak child processes. Limit child
lifetime to that of parent.
Fixes: https://github.com/nodejs/node/issues/9255
PR-URL: https://github.com/nodejs/node/pull/9257
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>