interrupt: fix send on closed
interrupt: fix send on closed

If we get a signal while shutting down, we could end up sending on a closed
channel.

License: MIT
Signed-off-by: Steven Allen <4068f0880b399410602d694b3cc711c8a8f4727e@stebalien.com>

Luzifer/go-ipfs,Luzifer/go-ipfs,Luzifer/go-ipfs