Tag to be used with the master branch of atlas/athena. Update(s) since 2.0.17: - Updated AnalysisBaseExternals to build TBB, and make the standalone version of ROOT build against that version of TBB; - Made it possible to build AnalysisBaseExternals on PPC64 and in C++17 mode; - Updated Acts to version 0.7.3; - Updates to CheckerGccPlugins for GCC 9; - Updated all projects to use LCG_94a.