Adapt/remove tests for the 2.13 stdlib.

All these changes come from the scala repo, most of them just remove
tests related to the parallel collections which are no longer part of
the stdlib.

tests/neg/equality.scala

@@ -119,14 +119,5 @@ object equality {
     s1 == Nil // error
     Nil == s2 // error
     s2 == Nil // error
-
-    import collection.parallel._
-    val p1 = ParSeq(1, 2, 3)
-    val p2 = ParSeq()
-    Nil == p1 // OK
-    p1 == Nil // OK
-    Nil == p2 // OK
-    p2 == Nil // Ok
-
   }
 }

tests/pos/sudoku.scala

@@ -1,3 +1,5 @@
+import scala.io.StdIn.readLine
+
 object SudokuSolver extends App {
   // The board is represented by an array of strings (arrays of chars),
   // held in a global variable m. The program begins by reading 9 lines

tests/run/array-charSeq.scala

@@ -1,12 +1,13 @@
+import runtime.ArrayCharSequence
+
 object Test {
   val arr = Array[Char]('a' to 'i': _*)
-  var xs: CharSequence = arr
+  var xs: CharSequence = new runtime.ArrayCharSequence(arr, 0, arr.length)
   val hash = xs.hashCode
 
   def check(chars: CharSequence): Unit = {
     println("\n[check '" + chars + "'] len = " + chars.length)
     chars match {
-      case x: Predef.ArrayCharSequence  => assert(x.__arrayOfChars eq arr, ((x.__arrayOfChars, arr)))
       case x: runtime.ArrayCharSequence => assert(x.xs eq arr, ((x.xs, arr)))
       case x                            => assert(false, x)
     }

tests/run/equality.scala

@@ -1,7 +1,7 @@
 // a quickly assembled test of equality.  Needs work.
 object Test
 {
-  import scala.runtime.ScalaRunTime.hash
+  def hash(x: Any): Int = x.## // forces upcast to Any
 
   def makeFromInt(x: Int) = List(
     x.toByte, x.toShort, x.toInt, x.toLong, x.toFloat, x.toDouble, BigInt(x), BigDecimal(x)