Change depthCor* static members to static std::atomic<> members for thread safety.
These parameters are set once in the PFCluster constructor from parameter set
or set once to default values in PFCluster.cc. After that they are only read.
Fix unused function warnings.
Merge pull request #2673 from degano/unused_warnings_fix_71X_gcc490

GCC 4.9.0 -- Fix unused function warnings.
Merge pull request #2664 from gartung/statics-DataFormats-ParticleFlowReco

Thread Safety  DataFormats/ParticleFlowReco -- Change depthCor* static members to static std::atomic
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X