TODO from https://github.com/fluxer/katana/issues/7. I've decided to
keep KDE4 and Katie libraries as PUBLIC, all other libraries as PRIVATE
for that and not use INTERFACE at all since that will not require a lot
of changes to all other sub-projects (kde-baseapps, kde-workspace and
kde-extraapps) build systems.
MusicBrainz5 CMake module was also rewritten as the actual library that
should be linked to is libmusicbrainz5cc, libmusicbrainz5 is the C
version of it.
common checks for X11 extensions where move to main config header,
eventually to be moved to separate config-x11 header.
Signed-off-by: Ivailo Monev <xakepa10@laimg.moc>
