[K/N][codegen] Fix for https://youtrack.jetbrains.com/issue/KT-48543

Sometimes an interface contains final methods, they shouldn't be in its itable
cause they can't be called virtually

kotlin-native/backend.native/tests/codegen/interfaceCallsNCasts/finalMethod.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package codegen.interfaceCallsNCasts.finalMethod
+
+import kotlin.test.*
+
+interface I1<T> {
+    fun defaultX(): T
+    fun foo(x: T = defaultX()): T
+}
+
+interface I2 : I1<Int> {
+
+}
+
+class C : I2 {
+    override fun defaultX() = 42
+    override fun foo(x: Int) = x
+}
+
+@Test
+fun runTest() {
+    val c: I2 = C()
+    assertEquals(42, c.foo())
+}