Fixed spawnSync ignoring its 'env' option

[ryotakatsuki]

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=

[cjihrig]

@ryotakatsuki84 can you please add tests.

[cjihrig]

This LGTM. It needs a test, which is provided in #8845

[bnoordhuis]

Thanks, landed in nodejs/node@ea945bf.

[trevnorris]

Thanks. Landed in 946cec7.