vmm(4): copyout guest state on VM_EXIT_NONE

vmm(4): copyout guest state on VM_EXIT_NONE

Partly related to a bug reported by kn@. We should be copying out
the guest exit state (including registers) when we succesfully
return from the vcpu run loop even if we don't require an emulation
assist from userland/vmd(8). This condition was introduced when I
removed the use of yield() and instead exit the kernel if the
scheduler says we've hogged the cpu.

ok mlarkin@