Fixes the problem also when passing path info as CMake parameters for
FairSoft/FairRoot apr21p2/v18.6.7.

The solution now works for CMake parameters as well as for environment variables
for bost FairSoft/FairRoot combinations apr21p2/v18.6.7 and nov22p1/v18.8.0.

MR 1680
(cherry picked from commit 3fd35831)