add [[cms::thread_safe]] to non-const function static var Registry::instance()::s_reg

[gartung]

No description provided.

[cmsbuild]

A new Pull Request was created by @gartung (Patrick Gartung) for CMSSW_7_0_X.

add [[cms::thread_safe]] to non-const function static var Registry::instance()::s_reg

It involves the following packages:

FWCore/ParameterSet

@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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@ktf you are the release manager for this.

[Dr15Jones]

+1

[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?