cmd/tailscaled,ipn/ipnlocal,wgengine/...: pass dns.Manager into netstack

Needed for a following commit which moves magicDNS handling into
netstack.

Signed-off-by: Tom DNetto <tom@tailscale.com>

ipn/ipnlocal/peerapi.go

@@ -864,7 +864,7 @@ func (h *peerAPIHandler) handleServeMagicsock(w http.ResponseWriter, r *http.Req
 	}
 	eng := h.ps.b.e
 	if ig, ok := eng.(wgengine.InternalsGetter); ok {
-		if _, mc, ok := ig.GetInternals(); ok {
+		if _, mc, _, ok := ig.GetInternals(); ok {
 			mc.ServeHTTPDebug(w, r)
 			return
 		}