Add serial support to Qt 5.6 for Windows 10 universal applications

Windows RT for 8.0/8.1 does not support access to using the system serial ports on a desktop/laptop computer so it's not possible for any serial access to be given on this OS, however in Windows 10 I have seen partial documentation that says universal applications (targetted for windows 10+) can now use the serial port, see https://github.com/dotMorten/NmeaParser/wiki/Using-in-a-Windows-Universal-App-%28SerialPort%29

It would be great if this support was added to Qt 5.6 (since its the first version of Qt that targets the Windows 10 Universal application API).