ifa leak on VNET teardown

[Kristof Provost]

On 13 Feb 2021, at 21:58, Alexander V. Chernikov wrote:
> It turns out we're leaking some ifas for loopback interfaces on VNET 
> teardown:
>
There’s a recent bug about this as well: 253998.
The problem’s been around for a long time though. The pf tests trigger 
it from time to time, although it doesn’t appear to be 100% 
consistent, so my current feeling is that it may be racy.

I see ‘in6_purgeaddr: err=65, destination address delete failed’ 
when we do leak, and I’ve also been able to confirm this is about the 
::1 IPv6 loopback address.

Best regards,
Kristof