Generate constructor without parameters if primary constructor has only parameters with default values

#KT-3085 Fixed

compiler/testData/codegen/defaultArguments/reflection/classInClassObject.kt

@@ -0,0 +1,8 @@
+class A {
+    class object {
+        class Foo(val a: Int = 1) {}
+    }
+}
+
+// CLASS: A$object$Foo
+// HAS_DEFAULT_CONSTRUCTOR: true