emulators/virtualbox-ose-legacy: Fix additions build on recent HEAD

Apply same fix used for the main port in commit ef04eff:

Src HEAD commit 6d3e78ad6c11 vfs_quotactl function signature, adapt
virtualbox code to be able to compile there too.

Reported by:	koobs, dim
MFH:		2021Q2

emulators/virtualbox-ose-legacy/files/patch-src_VBox_Additions_freebsd_vboxvfs_vboxvfs__vfsops.c

@@ -9,7 +9,7 @@
  /*
   * Copyright (C) 2008-2017 Oracle Corporation
   *
-@@ -14,245 +9,478 @@
+@@ -14,245 +9,482 @@
   * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
   * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
   */
@@ -539,7 +539,11 @@
 + * Do operation associated with quotas, not supported
 + */
 +static int
-+vboxfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg)
++vboxfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg
++#if __FreeBSD_version >= 1400018
++	, bool *mp_busy
++#endif
++	)
  {
 -    int rc;
 +	return (EOPNOTSUPP);