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/collections/SetOperationsTest/distinct.kt

@@ -0,0 +1,7 @@
+import kotlin.test.*
+
+
+fun box() {
+    assertEquals(listOf(1, 3, 5), listOf(1, 3, 3, 1, 5, 1, 3).distinct())
+    assertTrue(listOf<Int>().distinct().isEmpty())
+}

backend.native/tests/external/stdlib/collections/SetOperationsTest/distinctBy.kt

@@ -0,0 +1,7 @@
+import kotlin.test.*
+
+
+fun box() {
+    assertEquals(listOf("some", "cat", "do"), arrayOf("some", "case", "cat", "do", "dog", "it").distinctBy { it.length })
+    assertTrue(charArrayOf().distinctBy { it }.isEmpty())
+}

backend.native/tests/external/stdlib/collections/SetOperationsTest/intersect.kt

@@ -0,0 +1,9 @@
+import kotlin.test.*
+
+
+fun box() {
+    assertTrue(listOf(1, 3).intersect(listOf(5)).none())
+    assertEquals(listOf(5), listOf(1, 3, 5).intersect(listOf(5)).toList())
+    assertEquals(listOf(1, 3, 5), listOf(1, 3, 5).intersect(listOf(1, 3, 5)).toList())
+    assertTrue(listOf<Int>().intersect(listOf(1)).none())
+}

backend.native/tests/external/stdlib/collections/SetOperationsTest/plusAssign.kt

@@ -0,0 +1,21 @@
+import kotlin.test.*
+
+
+fun box() {
+    // lets use a mutable variable
+    var set = setOf("a")
+    val setOriginal = set
+    set += "foo"
+    set += listOf("beer", "a")
+    set += arrayOf("cheese", "beer")
+    set += sequenceOf("bar", "foo")
+    assertEquals(setOf("a", "foo", "beer", "cheese", "bar"), set)
+    assertTrue(set !== setOriginal)
+
+    val mset = mutableSetOf("a")
+    mset += "foo"
+    mset += listOf("beer", "a")
+    mset += arrayOf("cheese", "beer")
+    mset += sequenceOf("bar", "foo")
+    assertEquals(set, mset)
+}

backend.native/tests/external/stdlib/collections/SetOperationsTest/subtract.kt

@@ -0,0 +1,9 @@
+import kotlin.test.*
+
+
+fun box() {
+    assertEquals(listOf(1, 3), listOf(1, 3).subtract(listOf(5)).toList())
+    assertEquals(listOf(1, 3), listOf(1, 3, 5).subtract(listOf(5)).toList())
+    assertTrue(listOf(1, 3, 5).subtract(listOf(1, 3, 5)).none())
+    assertTrue(listOf<Int>().subtract(listOf(1)).none())
+}

backend.native/tests/external/stdlib/collections/SetOperationsTest/union.kt

@@ -0,0 +1,7 @@
+import kotlin.test.*
+
+
+fun box() {
+    assertEquals(listOf(1, 3, 5), listOf(1, 3).union(listOf(5)).toList())
+    assertEquals(listOf(1), listOf<Int>().union(listOf(1)).toList())
+}