added x11-drivers/xf86-video-virtualbox-4.3.10 from official tree
xf86-video-virtualbox-4.3.10: added FreeBSD support (includes fix for 3D support)
added app-emulation/virtualbox-guest-additions-4.3.10 from official tree
virtualbox-guest-additions-4.3.10: added FreeBSD support
xf86-video-virtualbox: added some patches from official tree