Work around bug in ROOT which affects split classes with iorules

[Dr15Jones]

If an iorule is attached to a class rather than a builtin type then
if that class is split in the TFile the iorule will not be run. This
change attached the rule to an additional member which is an int.

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for CMSSW_7_4_X.

Work around bug in ROOT which affects split classes with iorules

It involves the following packages:

DataFormats/Candidate

@nclopezo, @cvuosalo, @monttj, @cmsbuild, @slava77, @vadler can you please review it and eventually sign? Thanks.
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[Dr15Jones]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[cmsbuild]

-1
Tested at: fdd8500
The relvals timed out after 1 hour.

you can see the results of the tests here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-8496/6837/summary.html

[slava77]

+1

for #8496 fdd8500
jenkins tests are ok (nothing is broken)
I didn't try to reproduce the issue fixed by this bugfix

[Dr15Jones]

@davidlange6 ping?