add a few consts

[davidlange6]

fixing compilation error in IB

[davidlange6]

@mdhildreth - I'm pushing this into the IB as there is compilation error with the current version… pls confirm this is ok...

[cmsbuild]

A new Pull Request was created by @davidlange6 (David Lange) for CMSSW_7_1_X.

add a few consts

It involves the following packages:

SimGeneral/DataMixingModule

@cmsbuild, @civanch, @Degano, @mdhildreth, @nclopezo can you please review it and eventually sign? Thanks.
@wmtan 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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@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.
This pull requests was done for a production branch and will require explicit ORP approval on friday or L1 override.