Revert "Made mutable in EventSetupRecord atomic"

[ktf]

This reverts commit 64bd0d4.

[cmsbuild]

A new Pull Request was created by @ktf (Giulio Eulisse) for CMSSW_7_1_X.

Revert "Made mutable in EventSetupRecord atomic"

It involves the following packages:

FWCore/Framework

@cmsbuild, @Degano, @Dr15Jones, @ktf, @nclopezo can you please review it and eventually sign? Thanks.
@wmtan this is something you requested to watch as well.
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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.

[ktf]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_1_X IBs unless changes or unless it breaks tests. @nclopezo, @ktf can you please take care of it?