TrackerHitAssociator clear maps each new event

[wmtford]

Just implement the minimal fix suggested by Dmitrijus to prevent the memory leak from the TrackerHitAssociator in CMSSW_7_5_0_pre2. I'll need to invest some effort to understand the consumes changes made by David Lange and Bill Tanenbaum, before attempting any more ambitious cure. I also haven't tested anything beyond compilation. So I leave to reviewers to decide whether to go with this PR as a quick fix or look for something better.

[cmsbuild]

A new Pull Request was created by @wmtford (Bill Ford) for CMSSW_7_5_X.

TrackerHitAssociator clear maps each new event

It involves the following packages:

SimTracker/TrackerHitAssociation

@cmsbuild, @civanch, @nclopezo, @mdhildreth can you please review it and eventually sign? Thanks.
@makortel, @GiacomoSguazzoni, @rovere, @VinInn, @appeltel, @cerati, @threus, @dgulhan, @venturia this is something you requested to watch as well.
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@nclopezo you are the release manager for this.
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[civanch]

please test

[civanch]

+1

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[cmsbuild]

-1
Tested at: baf3799
you can see the results of the tests here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8819/4345/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_5_X IBs unless changes (but tests are reportedly failing). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @nclopezo, @ktf, @smuzaffar

[Dr15Jones]

The failure was due to DAS