kio-extras and the KF5/KF6 period

[Albert Astals Cid]

kio-extras provides plugins for kio.

So KF5 applications want a KF5 kio-extras and KF6 applications want a KF6 kio-
extras.

If we're going to support a period on which we ship both Kf5 and KF6 based 
applications we need to:

Make sure kf5 and kf6 are coinstallable.

a) release two tarballs, one for each KF
b) release one tarball that compiles both for kf5 and kf6 
c) just release the kf6 tarball, stop releasing the kf5 tarball but ask 
distributions to still install it


What's everyone's preference?

Cheers,
  Albert