Specify fno-omit-frame-pointer on OSX to all for proper stacktrace output.
Add mono_backtrace_from_context to properly retrieve a backtrace when altstack is being used. OSX only at the moment.
Move variable declaration to beginning of scope.
Only walk the specified number of frames in mono_backtrace_from_context.
Merge pull request #85 from Unity-Technologies/unity-staging

OSX Stack Trace Fixes