ReadEDM4hep: add message about enabling or disabling the reader

DDG4/CMakeLists.txt

@@ -116,7 +116,10 @@ IF(TARGET EDM4HEP::edm4hep)
       )
       install(TARGETS DDG4EDM4HEPReader EXPORT DD4hep LIBRARY DESTINATION lib)
       set_target_properties(DDG4EDM4HEPReader PROPERTIES VERSION ${DD4hep_VERSION} SOVERSION ${DD4hep_SOVERSION})
-    endif()
+      MESSAGE(STATUS "EDM4hepFileReader enabled")
+  else()
+      MESSAGE(STATUS "EDM4hepFileReader requires a new version of EDM4hep, disabled")
+  endif()
 ENDIF()
 
 IF(DD4HEP_USE_HEPMC3)