I'm not saying it works, but it compiles.
Updates #5794
Change-Id: I2f3c99732e67fe57a05edb25b758d083417f083e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
There are cases where we do not detect the non-viability of a route, but
we will instead observe a failure to send. In a Disco path this would
normally be handled as a side effect of Disco, which is not available to
non-Disco WireGuard nodes. In both cases, recognizing the failure as
such will result in faster convergence.
Updates #8999
Signed-off-by: James Tucker <james@tailscale.com>