RecoTauTag/RecoTau: clean -Wunused-function warnings

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #2557 from davidlt/clean-unused-function-RecoTauTag-RecoTau

GCC 4.9.0 -- RecoTauTag/RecoTau: clean -Wunused-function warnings