Ignore new ROOT error message about TH1 nbins <=0

When we switched to ROOT 5.34.17 a new warning message appeared
when TH1 is passed nbins <= 0. Since ROOT already sets the value
to nbins=1 we can ignore this warning.

Conflicts:
	FWCore/Services/src/InitRootHandlers.cc
Merge pull request #2756 from Dr15Jones/ignoreNBinsZero_7_1_X

ROOT 5.34.17 -- Ignore new ROOT error message about TH1 nbins <=0
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X