Fix check files to make build work again (#24595)

Author: odersky

tests/neg-custom-args/captures/consume-tvar-bound.check

@@ -1,22 +1,17 @@
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/consume-tvar-bound.scala:9:44 ----------------------------
-9 |def hh[T <: Ref^](x: Box[T]): (Ref^, Int) = (x.elem, 1) // error (but msg is strange since it does not highlight the underlying box conflict)
-  |                                            ^^^^^^^^^^^
-  |                                   Found:    (T^'s1, Int)
-  |                                   Required: (Ref^, Int)
-  |
-  |                                   Note that capability cap is not included in capture set {}.
-  |
-  |                                   where:    ^   refers to a fresh root capability in the result type of method hh
-  |                                             cap is a fresh root capability in the type of type T
-  |
-  | longer explanation available when compiling with `-explain`
 -- Error: tests/neg-custom-args/captures/consume-tvar-bound.scala:7:29 -------------------------------------------------
 7 |def h[T <: Ref^](x: Box[T]): Ref^ = x.elem // error
   |                             ^^^^
   |                  Separation failure: method h's result type Ref^ hides cap, which appears in the bound of type T.
   |                  This is not allowed. The type T has to be returned explicitly in the result type.
   |
   |                  where:    cap is a fresh root capability in the type of type T
+-- Error: tests/neg-custom-args/captures/consume-tvar-bound.scala:9:30 -------------------------------------------------
+9 |def hh[T <: Ref^](x: Box[T]): (Ref^, Int) = (x.elem, 1) // error (but msg is strange since it does not highlight the underlying box conflict)
+  |                              ^^^^^^^^^^^
+  |          Separation failure: method hh's result type (Ref^, Int) hides cap, which appears in the bound of type T.
+  |          This is not allowed. The type T has to be returned explicitly in the result type.
+  |
+  |          where:    cap is a fresh root capability in the type of type T
 -- Error: tests/neg-custom-args/captures/consume-tvar-bound.scala:11:37 ------------------------------------------------
 11 |def g[T <: Ref^](consume x: Box[T]): Ref^ = x.elem // error
    |                                     ^^^^

tests/pos-custom-args/captures/i24543.scala

@@ -0,0 +1,13 @@
+import scala.language.experimental.captureChecking
+// no separation checking
+
+class Ref
+case class Box[T](elem: T)
+
+def h1[T <: Ref^](x: Box[T]): Unit =
+  val y: (Ref^, Int) = (x.elem, 1) // would be sep error
+
+def h2[T <: Ref^](x: List[T]): (Ref^, Int) = (x.head, 1) // would be sep error
+
+
+