Making it possible to build Gaudi against a freely named ATLAS project

As described in a private e-mail, we need this change in the code to be able to build Gaudi for our analysis release with CMake. As in that setup the base project to build Gaudi against is called AthAnalysisBaseExternals, and not AtlasExternals.

Approved this merge request

Hi @clemenci,

Could you have a look? I think this change should not affect anyone but ATLAS. (We already have this update in our own repository's production branches.)

Cheers, Attila

Approved this merge request

Status changed to merged

mentioned in commit 90676f0e

Milestone changed to %v28r0

Reassigned to @clemenci

Mentioned in commit atlas/Gaudi@90676f0e