Subset of FreeBSD sources containing BHyve and some system libs - to work on a proper GPU pass through

While non-bhyve sources are based on stable/12, bhyve itself is updated to CURRENT.

https://envytools.readthedocs.io/en/latest/hw/bus/bars.html https://download.nvidia.com/XFree86/Linux-x86_64/440.59/README/ https://wiki.qemu.org/Documentation https://wiki.osdev.org/PCI

Some code was borrowed from Henrik Gulbrandsen who was working on expansion ROM support in July 2019. He posted his work up on https://www.gulbra.net/freebsd-bhyve/