Don't generate unnecessary accessors for private class properties

compiler/testData/codegen/box/properties/privatePropertyInConstructor.kt

@@ -0,0 +1,18 @@
+class A(
+        private val x: String,
+        private var y: Double
+) {
+    fun foo() {
+        val r = {
+            if (x != "abc") throw AssertionError("$x")
+            y = 0.0
+            if (y != 0.0) throw AssertionError("$y")
+        }
+        r()
+    }
+}
+
+fun box(): String {
+    A("abc", 3.14).foo()
+    return "OK"
+}