Update libresolv usage

dns/transport/local/resolv_darwin_cgo.go

@@ -20,7 +20,8 @@ import (
 )
 
 func dnsReadConfig(_ context.Context, _ string) *dnsConfig {
-	if C.res_init() != 0 {
+	var state C.res_state
+	if C.res_ninit(state) != 0 {
 		return &dnsConfig{
 			servers:  defaultNS,
 			search:   dnsDefaultSearch(),
@@ -33,10 +34,10 @@ func dnsReadConfig(_ context.Context, _ string) *dnsConfig {
 	conf := &dnsConfig{
 		ndots:    1,
 		timeout:  5 * time.Second,
-		attempts: int(C._res.retry),
+		attempts: int(state.retry),
 	}
-	for i := 0; i < int(C._res.nscount); i++ {
-		ns := C._res.nsaddr_list[i]
+	for i := 0; i < int(state.nscount); i++ {
+		ns := state.nsaddr_list[i]
 		addr := C.inet_ntoa(ns.sin_addr)
 		if addr == nil {
 			continue
@@ -44,7 +45,7 @@ func dnsReadConfig(_ context.Context, _ string) *dnsConfig {
 		conf.servers = append(conf.servers, C.GoString(addr))
 	}
 	for i := 0; ; i++ {
-		search := C._res.dnsrch[i]
+		search := state.dnsrch[i]
 		if search == nil {
 			break
 		}