data deprecations (empty constructors, non val/var arguments, vararg, superclasses) are now errors, relevant tests fixed

compiler/testData/codegen/boxWithStdlib/dataClasses/tostring/alreadyInherited.kt

@@ -1,10 +0,0 @@
-abstract class SuperTrait {
-  override fun toString(): String = "!"
-}
-
-data class A(val x: Int): SuperTrait() {
-}
-
-fun box(): String {
-  return if (A(0).toString() == "!") "OK" else "fail"
-}

compiler/testData/codegen/boxWithStdlib/dataClasses/tostring/mixedParams.kt

@@ -1,7 +1,7 @@
-data class A(var x: Int, y: Int, val z: Int?)
+data class A(var x: Int, val z: Int?)
 
 fun box(): String {
-    val a = A(1, 2, null)
+    val a = A(1, null)
     if("$a" != "A(x=1, z=null)") return "$a"
     return "OK"
 }