skip unix socket mode for windows

fix https://github.com/chrislusf/seaweedfs/issues/3013

weed/s3api/s3api_server.go

@@ -54,7 +54,7 @@ func NewS3ApiServer(router *mux.Router, option *S3ApiServerOption) (s3ApiServer
 		randomClientId: util.RandomInt32(),
 		filerGuard:     security.NewGuard([]string{}, signingKey, expiresAfterSec, readSigningKey, readExpiresAfterSec),
 	}
-	if option.LocalFilerSocket == nil {
+	if option.LocalFilerSocket == nil || *option.LocalFilerSocket == "" {
 		s3ApiServer.client = &http.Client{Transport: &http.Transport{
 			MaxIdleConns:        1024,
 			MaxIdleConnsPerHost: 1024,