Fix VirtualBox build on recent head and 13 after src commit
0659df6faddf

PR: 252675
Submitted by: O. Hartmann <ohartmann@walstatt.org>

		Mateusz Piotrowski <0mp@FreeBSD.org> (duplicate)

Reported by: se (mailing lists), others
Approved by: ports-secteam (fluffy)
MFH: 2020Q1