[IR][Native] Fix invalid IR return statement generation

^KT-46836

kotlin-native/backend.native/tests/codegen/function/unreachableStatementAfterReturn.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package codegen.function.unreachable_statement_after_return
+
+fun test1(): Any? {
+    return 1
+    42
+}
+
+fun test2(): Int? {
+    return 2
+    42
+}
+
+fun test3(): Any {
+    return 3
+    42
+}
+
+fun test4(): Int {
+    return 4
+    42
+}
+
+fun main() {
+    println(test1())
+    println(test2())
+    println(test3())
+    println(test4())
+}
+