Thread safety fix for MagneticField/Engine: Member data modified in const function

[smuzaffar]

use of atomic to avoid

• Member data modified in const function

Static analyzer will still report it as mutable member are still needed.

[cmsbuild]

A new Pull Request was created by @smuzaffar (Malik Shahzad Muzaffar) for CMSSW_7_0_X.

Thread safety fix for MagneticField/Engine: Member data modified in const function

It involves the following packages:

TrackingTools/TrajectoryState
TrackingTools/MaterialEffects
TrackingTools/TrajectoryParametrization
RecoTracker/TkSeedGenerator
MagneticField/Engine

@nclopezo, @cmsbuild, @thspeer, @slava77 can you please review it and eventually sign? Thanks.
@gpetruc, @cerati, @ghellwig, @GiacomoSguazzoni, @rovere 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.
You can reject by replying to this message having '-1' in the first line of your reply.
@ktf you are the release manager for this.

[cmsbuild]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/1395/summary.html

[thspeer]

+1
Tested 172f652 in CMSSW_7_0_X_2013-11-19-0200-1497
No difference in reco as expected, based on RelMon and reco script

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next IBs unless changes or unless it breaks tests. @ktf can you please take care of it?