Use anonymous namespace to avoid duplicate symbols

[wmtan]

This is a backport from 7_6_X #11066 and 7_5_X #11069 as requested by Slava Krutelyov
Bug fix. Totally technical.
In RecoEgamma/EgammaTools/plugins, there are free function templates in different files that have the same signature. These are violations of the ODR (one definition rule).
The reason this problem has not yet been seen before is that the function templates in question are declared "inline". However, "inline" is only a suggestion to the compiler. When compiled in debug mode (-O0), in-lining was apparently turned off. This did not cause a link error, as function templates are not instantiated until run time. However, it caused the wrong function to be called in several cases, causing relvals 4.53, 135.4, and 1330.0 to fail.
The fix is to put the templates inside an anonymous namespace, so each template is not seen outside the compilation unit. This fixes the failing relvals.

[Dr15Jones]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

A new Pull Request was created by @wmtan for CMSSW_7_4_X.

Use anonymous namespace to avoid duplicate symbols

It involves the following packages:

RecoEgamma/EgammaTools

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
@Sam-Harper, @lgray 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.
If you are a L2 or a release manager you can ask for tests by saying 'please test' in the first line of a comment.
@Degano 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
Tested at: 88640e0
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11265/8105/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11265/8105/summary.html

[slava77]

+1

for #11265 88640e0

• changes in the code are as described (anonymous namespace added)
• jenkins tests pass and comparisons with baseline show no difference

... we have an overlapping edit in #11282 in RecoEgamma/EgammaTools/plugins/EGExtraInfoModifierFromDB.cc , but there is a separation in context of about 200 lines. So, both PRs should still merge independently.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs once checked with relvals in the development release cycle of CMSSW (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1