Fastsim configs were not derived properly in 4878

While preparing #4878, the latest HLT menus for FastSim were not derived properly.

This pull request fixes it, thus avoiding crashes as in 
https://cmssdt.cern.ch/SDT/cgi-bin/buildlogs/slc6_amd64_gcc481/CMSSW_7_2_X_2014-08-06-0200/addOnTests/logs/cmsDriver-fastsim4_cmsRun__build_cmsbuild_jenkins-workarea_workspace_validatation-CMSSW_7_2_X-slc6_amd64_gcc481_cms_slc6_amd64_gcc481_cms_cmssw_CMSSW_7_2_X_2014-08-06-02.log