Do not require exclusive VNC access while buildling

An additional client can be connected during build time for inspection.
We can manually connect and set our VNC clients to ignore all input or
we can connect with vnc2flv to record the build session for later
verification.

builder/qemu/step_type_boot_command.go

@@ -52,7 +52,7 @@ func (s *stepTypeBootCommand) Run(state multistep.StateBag) multistep.StepAction
 	}
 	defer nc.Close()
 
-	c, err := vnc.Client(nc, &vnc.ClientConfig{Exclusive: true})
+	c, err := vnc.Client(nc, &vnc.ClientConfig{Exclusive: false})
 	if err != nil {
 		err := fmt.Errorf("Error handshaking with VNC: %s", err)
 		state.Put("error", err)

builder/vmware/common/step_type_boot_command.go

@@ -57,7 +57,7 @@ func (s *StepTypeBootCommand) Run(state multistep.StateBag) multistep.StepAction
 	}
 	defer nc.Close()
 
-	c, err := vnc.Client(nc, &vnc.ClientConfig{Exclusive: true})
+	c, err := vnc.Client(nc, &vnc.ClientConfig{Exclusive: false})
 	if err != nil {
 		err := fmt.Errorf("Error handshaking with VNC: %s", err)
 		state.Put("error", err)