x86/mce: add compat struct checking for XEN_MC_inject_v2

x86/mce: add compat struct checking for XEN_MC_inject_v2

84e364f2eda2 ("x86: add CMCI software injection interface") merely made
sure things would build, without any concern about things actually
working:
- despite the addition of xenctl_bitmap to xlat.lst, the resulting macro
  wasn't invoked anywhere (which would have lead to recognizing that the
  structure appeared to have no fully compatible layout, despite the use
  of a 64-bit handle),
- the interface struct itself was neither added to xlat.lst (and the
  resulting macro then invoked) nor was any manual checking of
  individual fields added.

Adjust compat header generation logic to retain XEN_GUEST_HANDLE_64(),
which is intentionally layed out to be compatible between different size
guests. Invoke the missing checking (implicitly through CHECK_mc).

No change in the resulting generated code.

Fixes: 84e364f2eda2 ("x86: add CMCI software injection interface")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>