Getting ecm files from the ECM package

[Stephen Kelly]

Alexander Neundorf wrote:

> find_package(KF5 ... COMPONENTS karchive solid kcompletion)
> 
> call in their CMakeLists.txt and get the same results.
> And if this works for tier3 libs, why not just do the same in tier2 and
> also in tier1...

Because tier1 doesn't depend on or find KF5 at all, by definition.

Anyway, I've made the first part of this change. Soon I will push followup 
changes to kf5-dependent repos to use the new KF5Config.cmake files I've 
just added.

Thanks,

Steve.