Use Consistent Qt style for ifdef

[ann0see]

Are the Windows and Android ones okay? Is the Q_ a "Qt" thing that we can use for all platforms? What's the OT_ thing?

Originally posted by @pljones in https://github.com/jamulussoftware/jamulus/pull/3360#discussion_r1770578872

The code should be refactored such that only one style is used. Probably Q_OS_WIN: https://doc.qt.io/qt-5/qtglobal.html#Q_OS_WIN

[softins]

The OT_ thing is just an enum within the Jamulus code, for the protocol byte that indicates the OS type:

https://github.com/jamulussoftware/jamulus/blob/d6c6fc7fde83d43612c926fcb20610ce0de26202/src/util.h#L1062-L1074

[ann0see]

Yes, I commented that in the respective PR.