[K/N][IR] Generate missing return when using Nothing-returning safe call as lambda result or function expression body

^KT-42832

kotlin-native/backend.native/tests/codegen/function/nothingNReturningSafeCall1.kt

@@ -0,0 +1,18 @@
+/*
+ * 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.nothingN_returning_safe_call1
+
+import kotlin.test.*
+
+fun Any.nothing(): Nothing {
+    while (true) {}
+}
+
+fun foo(obj: Any?): Nothing? = obj?.nothing()
+
+fun main() {
+    foo(null)
+}

kotlin-native/backend.native/tests/codegen/function/nothingNReturningSafeCall2.kt

@@ -0,0 +1,23 @@
+/*
+ * 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.nothingN_returning_safe_call2
+
+import kotlin.test.*
+
+fun Any.nothing(): Nothing {
+    while (true) {}
+}
+
+fun foo() {
+    val block: (Any?) -> Nothing? = {
+        it?.nothing()
+    }
+    block(null)
+}
+
+fun main() {
+    foo()
+}