added option to display stack traces in output for heap checker

Quoting from email:

I had the same question as William posted to stack overflow back on
Dec 9,2013: How to display symbols in stack trace of google-perftools
heap profiler (*).  I dug into the source and realized the
functionality was not there but could be added. I am hoping that
someone else will find this useful/helpful.

The patch I created will not attach so I am adding below.

Enjoy!

-- Michael

* http://stackoverflow.com/questions/20476918/how-to-display-symbols-in-stack-trace-of-google-perftools-heap-profiler