ipn/ipnlocal: return early, outdent a bunch in dnsConfigForNetmap

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/local.go

@@ -1838,7 +1838,10 @@ func dnsConfigForNetmap(nm *netmap.NetworkMap, prefs *ipn.Prefs, logf logger.Log
 		dcfg.Hosts[fqdn] = append(dcfg.Hosts[fqdn], ip)
 	}
 
-	if prefs.CorpDNS {
+	if !prefs.CorpDNS {
+		return dcfg
+	}
+
 	addDefault := func(resolvers []dnstype.Resolver) {
 		for _, r := range resolvers {
 			dcfg.DefaultResolvers = append(dcfg.DefaultResolvers, normalizeResolver(r))
@@ -1905,7 +1908,7 @@ func dnsConfigForNetmap(nm *netmap.NetworkMap, prefs *ipn.Prefs, logf logger.Log
 		// We don't support split DNS at all on Android yet.
 		addDefault(nm.DNS.FallbackResolvers)
 	}
-	}
+
 	return dcfg
 }