Multithreading cleanup up in GeomDet

[wddgit]

Add const to the declaration of a function
return type. The returned pointer was not
being used to modify anything. Eliminates
a static analyzer warning.

[cmsbuild]

A new Pull Request was created by @wddgit (W. David Dagenhart) for CMSSW_7_1_X.

Multithreading cleanup up in GeomDet

It involves the following packages:

Alignment/ReferenceTrajectories
Geometry/CommonDetUnit

@civanch, @diguida, @ianna, @mdhildreth, @cmsbuild, @Dr15Jones, @rcastello, @Degano, @ktf, @nclopezo can you please review it and eventually sign? Thanks.
@ghellwig, @mmusich, @frmeier 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.
@nclopezo, @ktf you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[cmsbuild]

+1
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-3829/1480/summary.html

[ktf]

Trivial. Bypassing AlCa & Geometry signature.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-3829/1480/summary.html