Fix a minor error in DQM/L1TMonitor BuildFile

[dmitrijus]

It needs to generate a proper edm plugin.

(backport of #13619)

[cmsbuild]

A new Pull Request was created by @dmitrijus (Dmitrijus) for CMSSW_8_0_X.

It involves the following packages:

DQM/L1TMonitor

@cmsbuild, @vanbesien, @deguio, @davidlange6 can you please review it and eventually sign? Thanks.
@slava77, @Degano, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[deguio]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/11750/console

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_0_X IBs after it passes the integration tests. This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[cmsbuild]

Comparison not run due to Fireworks only changes (RelVals and Igprof tests were also skipped)

[cmsbuild]

-1
Tested at: 21883e1
I found an error when building:

L1TSync_Offline.cc:(.text+0x50c5): undefined reference to `L1TMenuHelper::L1TMenuHelper(edm::EventSetup const&)'
L1TSync_Offline.cc:(.text+0x50ec): undefined reference to`L1TMenuHelper::testAlgos(std::map, std::allocator > > const&)'
L1TSync_Offline.cc:(.text+0x51f0): undefined reference to `L1TMenuHelper::getLUSOTrigger(std::map, std::allocator > > const&, int, L1GtUtils const&)'
L1TSync_Offline.cc:(.text+0x5a9d): undefined reference to`L1TMenuHelper::~L1TMenuHelper()'
L1TSync_Offline.cc:(.text+0x5d88): undefined reference to `L1TMenuHelper::~L1TMenuHelper()'
collect2: error: ld returned 1 exit status
gmake: **\* [tmp/slc6_amd64_gcc493/src/DQMOffline/L1Trigger/src/DQMOfflineL1Trigger/libDQMOfflineL1Trigger.so] Error 1
Leaving library rule at DQMOffline/L1Trigger
--- Registered EDM Plugin: DQMServicesStreamerIOPlugins
>> Leaving Package DQMServices/StreamerIO
>> Package DQMServices/StreamerIO built


you can see the results of the tests here:
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-13620/11750/summary.html

[deguio]

@dmitrijus
please fix this and re-submit to 81x (a new PR is needed there).
thanks,
F.

[deguio]

-1
the correct version of this PR should come from the backport of
#13691
F.