Sets some kvm_run out flags before going to userspace.
The out flags are:
1. exit_reason - this one was already handled
2. ready_for_interrupt_injection - true if
* IF_FLAG of rflags is 1
* we're not in an interrupt shadow (MOV SS, etc)
* kvm also checks its in-kernel interrupt queues, this commit just adds a
TODO for that
3. if_flag - simply read from rflags
4. ready_for_nmi_injection - this commit just adds a TODO
5. cr8 - this was read (in) but not set (out) before
6. apic_base - we're not using this, so this commit drops it from kvm_run
See also
99c9ffeefadb429accf27e11e558b89cb66eac04 for libfkvm, which assumed
some of this functionality.