Make Baloo detection and usage more subtle
Review Request #121140 - Created Nov. 16, 2014 and submitted
|davidedmundson, lukas, vhanda|
at the moment we have slightly messy situation.
there is baloo/5.1, and baloo master. we know gwenview will not build with < 5.1.90, that is master.
also resolved the old problem when user would select baloo backend, but it wasn't found, thus the build would fail in the middle.
inspected config-gwenview.h after passing various options (and locally raising required baloo version to 5.1.91)