nVMX x86: "virtualize APIC accesses" must be unset if "virtualize x2APIC" is set

According to section "Checks on VMX Controls" in Intel SDM vol 3C,
the following check needs to be enforced on vmentry of L2 guests:

    If the "virtualize x2APIC mode" VM-execution control is 1, the
    "virtualize APIC accesses" VM-execution control must be 0.

This unit-test validates the above vmentry check.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>