better Windows detection #16901

Not related to any actual issue, but I just came across this constant which should be more reliable and now with PHP 7.2 available for everyone.

PHP_OS_FAMILY (string)

The operating system family PHP was built for. One of 'Windows' , 'BSD' , 'Darwin' , 'Solaris' , 'Linux' or 'Unknown' . Available as of PHP 7.2.0.
https://www.php.net/manual/en/reserved.constants.php

Review

• [ ] Functional review done
• [ ] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• [ ] Security review done see checklist
• [ ] Code review done
• [ ] Tests were added if useful/possible
• [ ] Reviewed for breaking changes
• [ ] Developer changelog updated if needed
• [ ] Documentation added if needed
• [ ] Existing documentation updated if needed