cmd/tailscale: fix a panic in netcheck portmapper construction (#16843)

This affects the 1.87.33 unstable release.

Updates #16842
Updates #15160

Change-Id: Ie6d1b2c094d1a6059fbd1023760567900f06e0ad
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>

cmd/tailscale/cli/netcheck.go

@@ -61,6 +61,7 @@ func runNetcheck(ctx context.Context, args []string) error {
 	pm := portmapper.NewClient(portmapper.Config{
 		Logf:     logf,
 		NetMon:   netMon,
+		EventBus: bus,
 	})
 	defer pm.Close()