773-sigill-introspection

https://github.com/benoitc/gunicorn/issues/773

This feature is intended to help analyse the state of gunicorn processes in a given point of time. This can come handy when dealing with performance issues.

A new signal handler for SIGILL would be introduced which triggers the status dump. When the signal is received workers dump their current requests with stack traces to the /tmp dir. If the signal is sent to the master it will broadcast it to its workers.
We need it to be able to print the stack trace.