Turned off lowering of outer class for inner class constructors.

Constructors of inner classes already have access to their outer class
through its dispatch receiver parameter.

backend.native/tests/codegen/innerClass/secondaryConstructor.kt

@@ -0,0 +1,20 @@
+class Outer(val x: Int) {
+    inner class Inner() {
+        inner class InnerInner() {
+
+            init {
+                println(x)
+            }
+
+            lateinit var s: String
+
+            constructor(s: String) : this() {
+                this.s = s
+            }
+        }
+    }
+}
+
+fun main(args : Array<String>) {
+    Outer(42).Inner().InnerInner("zzz")
+}