Write correct InnerClasses attribute to class files

InnerClasses should contain entries for every inner and every outer class,
according to the JVMS

 #KT-3390 Fixed

compiler/testData/codegen/innerClassInfo/enumEntry.kt

@@ -0,0 +1,9 @@
+enum class E {
+    E1
+    
+    E2 {
+        override fun foo() {}
+    }
+    
+    open fun foo() {}
+}