xAODEventFormatCnv Fixes, master branch (2020.11.06.)
This is my counter-proposal to !37964 (closed).
Instead of creating a "fat" xAODEventFormatCnvTestLib library as !37964 (closed) does, this MR rather builds xAODEventFormatCnvTestLib to only hold the test xAOD EDM of the package. Then it sets up xAODEventFormatCnvTest to hold the source code of the components that it is creating, while linking against xAODEventFormatCnvTestLib of course. (Eliminating the need for modifying the source code of those components.)
The fixes to the build of xAODEventFormatCnvTestDict were done correctly in !37964 (closed) on the whole. Here I just removed the usage of ${ROOT_INCLUDE_DIR} from the configuration. Since it's not needed. The code of this package does not depend on ROOT directly. The dictionary generation does of course, but atlas_add_dictionary(...) takes care of that behind the scenes. There's no need to be explicit about that here.
Finally, the POOL converter library's dependencies needed to be revised a bit. So that it would link against exactly the libraries that it actually uses.