Baloo-widgets soversion

[Antonio Rojas]

> This could be easily fixed by passing a fixed SOVERSION argument to 
> ecm_setup_version(). But which one should be used? Would it be correct to 
> use 5 even if the library version is going to be YY.MM.DD ?

It should be 5 if there have been no ABI-breaking changes since 18.04 and 6 otherwise.

The soversion is meant to track backwards-incompatible ABI changes and is independent of the library version. For projects that follow a semantic versioning scheme it is customary that the soversion coincides with the major version number, but that's obviously not the case here.