We still have a bunch of Q_WS_ ifdefs in our code, which are easy to
mistake for Q_OS_ ifdefs when quickly scanning the code. By renaming
the ifdefs we make it clear that the code in question is dead.
In incremental follow-ups, we can then selectively either remove, or
port, the pieces that are dead code.
Change-Id: Ib5ef3e9e0662d321f179f3e25122cacafff0f41f
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>