Draft: Projects: Fix missing Vc dependency of ROOT with LCG_104

This MR fixes a missing Vc dependency of ROOT with LCG_104 in the AthSimulation project. More details in ATLINFR-5041.

Ideally this MR should be combined or comes after an update of atlasexternals that includes the MR atlasexternals!1039 (merged)

Keeping in Draft status until we can confirm that the Athena project or other projects will need a similar fix.

Projects/AthSimulation/CMakeLists.txt

@@ -33,6 +33,7 @@ find_package( TIFF )
 find_package( libffi )
 find_package( gl2ps )
 find_package( autopep8 )
+find_package( Vc )
 
 # Set the project into "SIMULATIONBASE mode".
 set( SIMULATIONBASE TRUE CACHE BOOL