Get rid of invalid benchmark

src/test/resources/regression/verification/newsolvers/valid/Choose1.scala

-/* Copyright 2009-2014 EPFL, Lausanne */
-
-import leon.annotation._
-import leon.lang.synthesis._
-import leon.lang._
-
-object Choose1 {
-    sealed abstract class List
-    case class Cons(head: Int, tail: List) extends List
-    case class Nil() extends List
-
-    def size(l: List) : BigInt = (l match {
-        case Nil() => BigInt(0)
-        case Cons(_, t) => 1 + size(t)
-    }) ensuring(res => res >= 0)
-
-    def content(l: List) : Set[Int] = l match {
-      case Nil() => Set.empty[Int]
-      case Cons(x, xs) => Set(x) ++ content(xs)
-    }
-
-    def listOfSize(i: BigInt): List = {
-      require(i >= 0)
-
-      if (i == BigInt(0)) {
-        Nil()
-      } else {
-        choose { (res: List) => size(res) == i }
-      }
-    } ensuring ( size(_) == i )
-
-
-    def listOfSize2(i: BigInt): List = {
-      require(i >= 0)
-
-      if (i > 0) {
-        Cons(0, listOfSize(i-1))
-      } else {
-        Nil()
-      }
-    } ensuring ( size(_) == i )
-}