Floating point exception in VPClusterEffSimDQ

When running Boole with VP, floating point exception was triggered at the following lines.

https://gitlab.cern.ch/lhcb/Lbcom/-/blob/master/VP/VPCheckers/src/VPClusterEffSimDQ.cpp#L187 https://gitlab.cern.ch/lhcb/Lbcom/-/blob/master/VP/VPCheckers/src/VPClusterEffSimDQ.cpp#L218