irqbalance never exits

[Andreas Schwab]

irqbalance fails to exit after SIGTERM because parse_proc_interrupts always sets need_rescan. This happens because of this line in /proc/interrupts:

161: 0 0 48059000.gpio 25 Edge button S2

[Neil Horman]

yeah, looks like the while (need_rescan | need_rebuild) { } loop needs to be augmented to be:
while (keep_going && (need_rescan || need_rebuild)) {}

I'm a bit tied up, can you submit a PR?