mount: change interface of mount commands to take mount options

This is in preparation of being able to pass mount options to the rc
command "mount/mount"

vfs/vfstest_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	_ "github.com/rclone/rclone/backend/all" // import all the backends
+	"github.com/rclone/rclone/cmd/mountlib"
 	"github.com/rclone/rclone/fstest"
 	"github.com/rclone/rclone/vfs"
 	"github.com/rclone/rclone/vfs/vfstest"
@@ -17,7 +18,7 @@ func TestFunctional(t *testing.T) {
 	if *fstest.RemoteName != "" {
 		t.Skip("Skip on non local")
 	}
-	vfstest.RunTests(t, true, func(VFS *vfs.VFS, mountpoint string) (unmountResult <-chan error, unmount func() error, err error) {
+	vfstest.RunTests(t, true, func(VFS *vfs.VFS, mountpoint string, opt *mountlib.Options) (unmountResult <-chan error, unmount func() error, err error) {
 		unmountResultChan := make(chan (error), 1)
 		unmount = func() error {
 			unmountResultChan <- nil