Change comment on gen particles (2012 branch)

[caredg]

https://github.com/cms-legacydata-analyses/PhysObjectExtractorTool/blob/42e213ee9d9a56ce28803b8a8ed5aa58160eac62/PhysObjectExtractor/python/poet_cfg.py#L207

Here, change comment to "status:pdgid" and specify that sign needs to be included (or change the code to an abs, I do not know what is best)