MFC r266933
Activate vcpus from bhyve(8) using the ioctl VM_ACTIVATE_CPU instead of doing
it implicitly in vmm.ko.
MFC r267216
Add ioctl(VM_REINIT) to reinitialize the virtual machine state maintained
by vmm.ko. This allows the virtual machine to be restarted without having
to destroy it first.
MFC r269387: Update the ARMv6 core clang targets to be an arm1176jzf-s.
MFC r267178, r267300

Support guest accesses to %cr8

Add reserved bit checking when doing %CR8 emulation and inject #GP if required.