Faulting pthread signal handlers abort

If the handler faults and tries to signal itself, we print the debug info and
abort the process.

Note the sighandler or the process in general can mask or override certain
handlers (like the PF handler) to not do anything.  In which case, the thread
will restart and refault, forever.  That's the process's fault.
Removes old documentation

More up-to-date stuff at:
https://github.com/klueska/go-akaros/blob/master/misc/akaros/README