Remove deadlock in ContainerWait

when `cli.post(...)` fails `errC <- err` blocks because `errC` is unbufferd.

Signed-off-by: Simon Menke <simon.menke@gmail.com>

client/container_wait.go

@@ -31,7 +31,7 @@ func (cli *Client) ContainerWait(ctx context.Context, containerID string, condit
 	}
 
 	resultC := make(chan container.ContainerWaitOKBody)
-	errC := make(chan error)
+	errC := make(chan error, 1)
 
 	query := url.Values{}
 	query.Set("condition", string(condition))