The lock file should be closed after opening it with openSync

[Mng12345]

https://github.com/rescript-lang/rescript-compiler/blob/432c513fee1bb4aeb04c7ceddde003a18cfc9818/rescript#L194
This code will not delete the lock file on Windows as the lock file is not closed.

const fs = require('fs');
let fId = fs.openSync('fk.lock', 'wx', 0o664);
fs.unlinkSync('fk.lock')

We should close it before deleting.

const fs = require('fs');
let fId = fs.openSync('fk.lock', 'wx', 0o664);
fs.closeSync(fId);
fs.unlinkSync('fk.lock');

This caused the build error on Windows.