Following on from my thread on the main list [1], I have made an initial 
attempt at implementing backtrace(3) and backtrace_symbols(3). This 
still needs a little work - at the moment, the paths in the strings will 
be DOS-style rather than POSIX. However, I wanted to submit an early 
version to make sure you were happy with my approach before I spend more 
time on it.

I've also documented (in the code) the issues surrounding 
backtrace_symbols_fd(3) on Cygwin.

This is my first real submission to the programme - be kind :-)

Dave.

[1] - http://cygwin.com/ml/cygwin/2015-03/msg00198.html