Add special '+dd4hep' platforms to PlatformInfo list
Fixes a test when using the special platform x86_64_v2-centos7-gcc10+dd4hep-opt
and prepare for the other foreseen +dd4hep
variants.
Fixes a test when using the special platform x86_64_v2-centos7-gcc10+dd4hep-opt
and prepare for the other foreseen +dd4hep
variants.