fix getcwd() usage to avoid undefined behavior

[dan131riley]

TFileService::afterBeginJob() abuses getcwd() in a way that depends on undefined behavior, breaking with gcc 6.3.0. This patch fixes the undefined behavior and makes it more robust handling long paths and other errors that never happen.

[cmsbuild]

A new Pull Request was created by @dan131riley (Dan Riley) for master.

It involves the following packages:

CommonTools/UtilAlgos

@perrotta, @cmsbuild, @slava77, @monttj, @davidlange6 can you please review it and eventually sign? Thanks.
@makortel this is something you requested to watch as well.
@Muzaffar, @davidlange6, @smuzaffar you are the release manager for this.

cms-bot commands are listed here #13028

[Dr15Jones]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/19425/console Started: 2017/04/26 20:55

[Dr15Jones]

+1

[cmsbuild]

+1
Tested at: 8ff1714
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-18485/19425/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-18485/19425/summary.html

Comparison Summary:

• You potentially added 12 lines to the logs
• Reco comparison results: 37 differences found in the comparisons
• DQMHistoTests: Total files compared: 23
• DQMHistoTests: Total histograms compared: 1783681
• DQMHistoTests: Total failures: 2278
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 1781230
• DQMHistoTests: Total skipped: 173
• DQMHistoTests: Total Missing objects: 0
• Checked 94 log files, 14 edm output root files, 23 DQM output files

[slava77]

+1

for #18485 8ff1714

• the changes appear to resolve issues with long path names
• jenkins tests pass