Avoid segfault in relval 50102 for gcc4.9.0

[wmtan]

Relval test 50102 segfaults in gcc4.9.0 IB's. This segfault was traced to DQMOffline/Trigger/src/TopSingleLeptonHLTOfflineDQM.cc, where a vector subscript is way out of bounds (not an off-by-one error).
This pull request simply adds an assert to check for this and avoid the segfault. It is up to the package owners to fix the underlying problem.
Note that there is no segfault in relval 50102 in gcc4.8.1 IB's. Also, this assert does not fire in relval 50102 in gcc4.8.1 IB's. I did not investigate the difference. But again, the package owners need to diagnose and fix the problem before there can be releases using gcc4.9.0.

[cmsbuild]

A new Pull Request was created by @wmtan for CMSSW_7_1_X.

Avoid segfault in relval 50102 for gcc4.9.0

It involves the following packages:

DQMOffline/Trigger

@ojeda, @danduggan, @rovere, @cmsbuild, @nclopezo, @deguio, @Degano can you please review it and eventually sign? Thanks.
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.
@nclopezo, @ktf you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[ojeda]

+1

Thanks for taking time investigating this, Bill.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_1_X IBs unless changes or unless it breaks tests. @nclopezo, @ktf can you please take care of it?

[ktf]

I've bypassed tests, since it's trivial.