Goal:
  
  A : Type
  P : A → Prop
  Q : A → Prop
  p : A → bool
  Hp : ∀ x : A, Q x → reflect (P x) (p x)
  ============================
   (forallb p [] = true → Forall P [])


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrrewrite@0> $1 $2