Fixed checksums and a bad merge from CMSSW_7_3_X

-Fixed checksum for reco::GsfElectron because of ROOT 6
-The new entry for reco::GsfElectron::PixelMatchVariables was missing
from the merge with CMSSW_7_3_X
Fixed checksum for ROOT 5.34.22

The checksum for pat::Electron had to be updated because of a change
to something the class depends upon. I reused 26 as the version number
since that number was only ever used in the _DEVEL branch anyway.
Merge pull request #6314 from Dr15Jones/fixMoreChecksums_THREADED

Fix more checksums