KVM: VMX: support MSR_IA32_ARCH_CAPABILITIES as a feature MSR

KVM: VMX: support MSR_IA32_ARCH_CAPABILITIES as a feature MSR

This lets userspace read the MSR_IA32_ARCH_CAPABILITIES and check that all
requested features are available on the host.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Orabug: 28220625
CVE: CVE-2018-3646

(cherry picked from commit cd28325249a1ca0d771557ce823e0308ad629f98)

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Conflicts:
	arch/x86/kvm/x86.c
Contextual: different content