Preparing alternative e-map handling in unpacker for 74X

[abdoulline]

This is to allow for (an instance of) unpacker to use alternative emap (with appropriate label) with customized string
ElectronicsMap = cms.string("")
NB: default " " means regular GT tag.

Identical to what's submitted to 75X - #8600

[cmsbuild]

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

Preparing alternative e-map handling in unpacker for 74X

It involves the following packages:

EventFilter/HcalRawToDigi

@cmsbuild, @cvuosalo, @nclopezo, @slava77 can you please review it and eventually sign? Thanks.
@Martin-Grunewald this is something you requested to watch as well.
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@Degano you are the release manager for this.
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[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

+1
Tested at: 1c0be73
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8610/6969/summary.html

[cvuosalo]

+1

For #8610 1c0be73

This PR enables the unpacker to use an alternative emap. It doesn't yet change the emap used, so it should not change run-time behavior.

The code changes are satisfactory, and Jenkins tests against baseline CMSSW_7_4_X_2015-03-30-2300 show no significant differences, as expected. The Jenkins comparisons completed only for a couple of workflows for reasons not related to this PR, but, for this simple PR, they are adequate.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs unless changes (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @ktf, @smuzaffar

[davidlange6]

+1