Generate private constructors for Enums

#KT-2680 Fixed
  #KT-16867 Fixed

compiler/testData/codegen/box/enum/annotatedParameter2.kt

@@ -0,0 +1,25 @@
+// TARGET_BACKEND: JVM
+// FILE: Foo.java
+
+public class Foo {
+
+    static String test() {
+        return KEnum.O.name() + KEnum.O.getValue();
+    }
+}
+
+
+
+// FILE: KEnum.kt
+@Retention(AnnotationRetention.RUNTIME)
+annotation class A
+
+enum class KEnum(@A val value: Any) {
+    O("K") {
+        fun foo() {}
+    }
+}
+
+fun box(): String {
+    return Foo.test()
+}