Print out instrumented program stacktrace on ASSERT

_From [timurrrr@google.com](https://code.google.com/u/timurrrr@google.com/) on August 03, 2011 08:39:34_

This is what we already have in Valgrind.

I believe this is really useful, e.g. see issue #532 c#4 - just a couple of lines of code and it's much easier to find the cause of a crash

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=536_