vbox builders now need to explicitly set WinRMPort for StepConnect

Aligns vbox builders with changes to helper/communicator/step_connect.go
introduced by PR #2576

Fixes #4310

builder/virtualbox/iso/builder.go

@@ -242,6 +242,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			Host:      vboxcommon.CommHost(b.config.SSHConfig.Comm.SSHHost),
 			SSHConfig: vboxcommon.SSHConfigFunc(b.config.SSHConfig),
 			SSHPort:   vboxcommon.SSHPort,
+			WinRMPort: vboxcommon.SSHPort,
 		},
 		&vboxcommon.StepUploadVersion{
 			Path: b.config.VBoxVersionFile,

builder/virtualbox/ovf/builder.go

@@ -116,6 +116,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			Host:      vboxcommon.CommHost(b.config.SSHConfig.Comm.SSHHost),
 			SSHConfig: vboxcommon.SSHConfigFunc(b.config.SSHConfig),
 			SSHPort:   vboxcommon.SSHPort,
+			WinRMPort: vboxcommon.SSHPort,
 		},
 		&vboxcommon.StepUploadVersion{
 			Path: b.config.VBoxVersionFile,