macOS doesn't have a way to detect this via the FIODTYPE ioctl(), so we have to resort to detecting the NUL device via major and minor version number. Fortunately, that hasn't changed since the inception of macOS.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55568
-- v3: ntdll: correctly detect the NUL device under macOS