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/ranges/CoercionTest/coercionsComparable.kt

@@ -0,0 +1,34 @@
+import kotlin.test.*
+
+
+private class ComparableNumber(val value: Int) : Comparable<ComparableNumber> {
+    override fun compareTo(other: ComparableNumber): Int = this.value - other.value
+    override fun toString(): String = "CV$value"
+}
+
+fun box() {
+    val v = (0..10).map { ComparableNumber(it) }
+
+    expect(5) { v[5].coerceAtLeast(v[1]).value }
+    expect(5) { v[1].coerceAtLeast(v[5]).value }
+    expect(v[5]) { v[5].coerceAtLeast(ComparableNumber(5)) }
+
+    expect(1) { v[5].coerceAtMost(v[1]).value }
+    expect(1) { v[1].coerceAtMost(v[5]).value }
+    expect(v[1]) { v[1].coerceAtMost(ComparableNumber(1)) }
+
+    for (value in v) {
+        expect(value) { value.coerceIn(null, null) }
+        val min = v[2]
+        val max = v[5]
+        val range = min..max
+        expect(value.coerceAtLeast(min)) { value.coerceIn(min, null) }
+        expect(value.coerceAtMost(max)) { value.coerceIn(null, max) }
+        expect(value.coerceAtLeast(min).coerceAtMost(max)) { value.coerceIn(min, max) }
+        expect(value.coerceAtMost(max).coerceAtLeast(min)) { value.coerceIn(range) }
+        assertTrue((value.coerceIn(range)) in range)
+    }
+
+    assertFails { v[1].coerceIn(v[1], v[0]) }
+    assertFails { v[1].coerceIn(v[1]..v[0]) }
+}