Add interop test for returning struct by value

backend.native/tests/build.gradle

@@ -1651,7 +1651,7 @@ task interop0(type: RunInteropKonanTest) {
 }
 
 task interop1(type: RunInteropKonanTest) {
-    goldValue = "257\n"
+    goldValue = "257\n-1\n-2\n"
     source = "interop/basics/1.kt"
     interop = 'cstdlib'
 }

backend.native/tests/interop/basics/1.kt

@@ -1,5 +1,12 @@
 import cstdlib.*
+import kotlinx.cinterop.*
 
 fun main(args: Array<String>) {
     println(atoi("257"))
+
+    val divResult = div(-5, 3)
+    val (quot, rem) = divResult.useContents { Pair(quot, rem) }
+    println(quot)
+    println(rem)
+
 }