Fixed spawnSync ignoring its 'env' option

spawnSync ignores its env option. It can be reproduced using the below snippet:

    var child_process = require('child_process');
    var r = child_process.spawnSync("bash", ['-c', 'echo FOO=$FOO'], { env: { FOO: 'BAR' }});
    console.log(r.stdout.toString());

The expected output should be: 

    FOO=BAR

But as the 'env' option is ignored, it simply prints:

    FOO=