ipn,log: add logger for sockstat deltas

Signed-off-by: Will Norris <will@tailscale.com>
Co-authored-by: Melanie Warrick <warrick@tailscale.com>

net/sockstats/sockstats_noop.go

@@ -9,6 +9,8 @@ import (
 	"context"
 )
 
+const IsAvailable = false
+
 func withSockStats(ctx context.Context, label Label) context.Context {
 	return ctx
 }