Dockerd: enable CORS when only `--api-cors-header` is used

Even though the flag `--api-enable-cors` is deprecated in favor of
`--api-cors-header`. Using only `--api-cors-header` does not enable
CORS.

Make changes to 'cmd/dockerd/daemon.go' to enable cors if either of
the above flags is set.

Signed-off-by: Karthik Nayak <Karthik.188@gmail.com>

cmd/dockerd/daemon.go

@@ -511,7 +511,7 @@ func (cli *DaemonCli) initMiddlewares(s *apiserver.Server, cfg *apiserver.Config
 	vm := middleware.NewVersionMiddleware(v, api.DefaultVersion, api.MinVersion)
 	s.UseMiddleware(vm)
 
-	if cfg.EnableCors {
+	if cfg.EnableCors || cfg.CorsHeaders != "" {
 		c := middleware.NewCORSMiddleware(cfg.CorsHeaders)
 		s.UseMiddleware(c)
 	}