Fix Geant4 LD_LIBRARY_PATH when using CLHEPConfig.cmake
When CLHEP is found via CLHEPConfig.cmake
instead of FindCLHEP.cmake
(as in LCG 97a), the runtime environment produced by GaudiProjectConfig.cmake
is not complete because CLHEPConfig.cmake
does not set some variables we rely on.
This change fixes the issue adding the missing variable.