syn_lwnheadline: Mozilla's "rr" debugger

Mozilla's "rr" debugger
Robert O'Callahan has posted an
announcement of a new record-and-replay debugger (called rr) from the Mozilla project.
"It's difficult to communicate the feeling of debugging with rr, but
if you've ever done something wrong during debugging (e.g. stepped too far)
and had that 'crap! Now I have to start all over again' sinking feeling ---
rr does away with that. Everything you already learned about the execution
--- e.g. the addresses of the objects that matter --- remains valid when
you start the next replay. Your understanding of the execution increases
monotonically."