fix to run Z->mumu alignment validation

Some fixes to run the Z->mumu alignment validation on 72X and SLC6 machines
@davidlange6. Thanks for the link.I meant that invoking `CompareBiasZValidation.C` from CINT [here](https://github.com/scasasso/cmssw/blob/PR_ZMuMu_BP72X/Alignment/OfflineValidation/python/TkAlAllInOneTool/zMuMuValidationTemplates.py#L259) just after a plain `cmsenv` fails.@scasasso My take is that this calls for having the RooFit application built from `CMSSW` as explained here: https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideRooFitCMSSW