Make version numbers consistent with 7_4_X

[wmtan]

The ROOT class version numbers for class pat::PackedCandidate have recently become inconsistent between 7_4_X and 7_5_X, in that version 23 is used for different checksums in the two releases.
Fortunately, the version actually used in 7_5_X (version 21) is consistent, so no harm has yet been done. Nonetheless, to prevent possible severe problems in the future, this PR makes the class versions in 7_5_X consistent with 7_4_X.
Since this is purely technical, it should be expedited.

[wmtan]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

A new Pull Request was created by @wmtan for CMSSW_7_5_X.

Make version numbers consistent with 7_4_X

It involves the following packages:

DataFormats/PatCandidates

@cmsbuild, @vadler, @monttj can you please review it and eventually sign? Thanks.
@gpetruc 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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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: 80a6aa4
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11365/8210/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11365/8210/summary.html