Misc errors and warnings cleanup in DQMOffline/Trigger

The following patchset cleanups all Clang reported errors and majority of reported warnings. Warnings from RooFit were [fixed today](http://root.cern.ch/gitweb?p=root.git;a=commitdiff;h=de35d07d9f9bde5ded6a97ddef4e0763d8e3a78a) for future 5.34.XX patch releases.

This is needed to compile with Clang.

Please, review.