[K/N] Use suspend function desugaring lowerings.

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

@@ -4,6 +4,7 @@
  */
 
 package codegen.function.unreachable_statement_after_return
+import kotlin.coroutines.*
 
 fun test1(): Any? {
     return 1
@@ -25,10 +26,42 @@ fun test4(): Int {
     42
 }
 
+suspend fun test5(): Any? {
+    return 5
+    42
+}
+
+suspend fun test6(): Int? {
+    return 6
+    42
+}
+
+suspend fun test7(): Any {
+    return 7
+    42
+}
+
+suspend fun test8(): Int {
+    return 8
+    42
+}
+
+@Suppress("UNCHECKED_CAST")
+private fun <T> (suspend () -> T).runCoroutine() : T {
+    var result : Any? = null
+    startCoroutine(Continuation(EmptyCoroutineContext) { result = it.getOrThrow() })
+    return result as T
+}
+
 fun main() {
     println(test1())
     println(test2())
     println(test3())
     println(test4())
+
+    println(::test5.runCoroutine())
+    println(::test6.runCoroutine())
+    println(::test7.runCoroutine())
+    println(::test8.runCoroutine())
 }
 

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

@@ -2,3 +2,7 @@
 2
 3
 4
+5
+6
+7
+8