Port #9130 to 741pX

[quertenmont]

Needed for HSCP signal DIGI-RECO in a bug-fixed release

[cmsbuild]

A new Pull Request was created by @quertenmont (Loic Quertenmont) for CMSSW_7_4_1_patchX.

Port #9130 to 741pX

It involves the following packages:

DQM/TrackingMonitor
DQM/TrackingMonitorSource
RecoTracker/DeDx

@cmsbuild, @cvuosalo, @danduggan, @deguio, @slava77 can you please review it and eventually sign? Thanks.
@ghellwig, @makortel, @GiacomoSguazzoni, @rovere, @VinInn, @appeltel, @mschrode, @cerati, @gpetruc, @istaslis, @threus, @dgulhan, @venturia this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
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Note that this branch is designed for requested bug fixes specific to the CMSSW_7_4_1 release.
If you wish to make a pull request for the CMSSW_7_4_X release cycle, please use the CMSSW_7_4_X branch instead