tests: Copy stdlib tests from Kotlin/JVM

This patch copies Kotlin/JVM stdlib tests (libraries/stdlib/test)
excepting ones with explicit java dependencies. It also transforms
the tests to use them as box-tests.

backend.native/tests/external/stdlib/OrderingTest/reversedComparator.kt

@@ -0,0 +1,18 @@
+import kotlin.test.*
+
+import kotlin.comparisons.*
+
+data class Item(val name: String, val rating: Int) : Comparable<Item> {
+    public override fun compareTo(other: Item): Int {
+        return compareValuesBy(this, other, { it.rating }, { it.name })
+    }
+}
+
+val v1 = Item("wine", 9)
+val v2 = Item("beer", 10)
+fun box() {
+    val comparator = compareBy<Item> { it.name }
+    val reversed = comparator.reversed()
+    assertEquals(comparator.compare(v2, v1), reversed.compare(v1, v2))
+    assertEquals(comparator, reversed.reversed())
+}