Make static theVerboseLevel const

The file static variable theVerboseLevel has no way of being changed
via code therefore it is safe to make it const. This avoids complaints
from the static analyzer.
Merge pull request #6392 from Dr15Jones/makeGlobalConstSiPixelTemplateReco

Make static theVerboseLevel const
Merge remote branch 'origin/CMSSW_7_3_X' into CMSSW_7_0_X