kvm-unit-tests : Basic architecture of VMX nested test case

This is the first version of VMX nested environment. It contains the
basic VMX instructions test cases, including VMXON/VMXOFF/VMXPTRLD/
VMXPTRST/VMCLEAR/VMLAUNCH/VMRESUME/VMCALL. This patchalso tests the
basic execution routine in VMX nested environment andlet the VM print
"Hello World" to inform its successfully run.

The first release also includes a test suite for vmenter (vmlaunch and
vmresume). Besides, hypercall mechanism is included and currently it is
used to invoke VM normal exit.

New files added:
x86/vmx.h : contains all VMX related macro declerations
x86/vmx.c : main file for VMX nested test case

Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>