UPPER DARBY >> Don't mess with Upper Darby cops.That's the often-stated mantra of top cop Mike Chitwood, who a few years back made headlines with his "not in my township" warning to criminals.Turns out it goes for some residents as well. They have their officers' backs.A township police officer still on the mend after a struggle with a suspect last month attended a recent council meeting to express his thanks to three of the four people who came to his aid.