Hint Resolve areg_sound aregs_sound: va.

Lemma abuiltin_args_sound:
forall bc ge rs sp m ae rm am,
ematch bc rs ae ->
romatch bc m rm ->
mmatch bc m am ->
genv_match bc ge ->
bc sp = BCstack ->
forall al vl,
eval_builtin_args ge (fun r => rs#r) (Vptr sp Ptrofs.zero) m al vl ->
list_forall2 (vmatch bc) vl (map (abuiltin_arg ae am rm) al).