toString() method for data classes and fake implementation for hashCode/equals

compiler/testData/codegen/dataClasses/tostring/arrayParams.kt

@@ -0,0 +1,14 @@
+data class A(val x: Array<Int>?, val y: IntArray?)
+
+fun box(): String {
+    var ts = A(Array<Int>(2, {it}), IntArray(3)).toString()
+    if(ts != "A{x=[0, 1], y=[0, 0, 0]}") return ts
+
+    ts = A(null, IntArray(3)).toString()
+    if(ts != "A{x=null, y=[0, 0, 0]}") return ts
+
+    ts = A(null, null).toString()
+    if(ts != "A{x=null, y=null}") return ts
+
+    return "OK"
+}