FreeBSD 11.0-RC1 regression with regard to mouse integration in VirtualBox 5.1.4

[David Boyd]

Using FreeBSD 10.3-RELEASE-p6 with virtualbox-guest-additions 5.0.26 on
VirtualBox 5.1.4 (CentOS EL7 host) as a baseline I didn't experience any
difficulties.

After fresh install of FreeBSD 11.0-RC1 with virtualbox-guest-additions
5.0.26 on VirtualBox 5.1.4 (CentOS EL7 host) mouse integration is
missing.

I have time and resources to test any changes you have to suggest.

Thanks.