Spread should always copy arrays.

Introduce a special (package private) utility class ArraysUtilJVM
to fix Array<T>.asList() issues.

compiler/testData/codegen/boxWithStdlib/vararg/spreadCopiesArray.kt

@@ -0,0 +1,27 @@
+import kotlin.test.*
+
+fun <T> copyArray(vararg data: T): Array<out T> = data
+
+inline fun <reified T> reifiedCopyArray(vararg data: T): Array<out T> = data
+
+fun copyIntArray(vararg data: Int): IntArray = data
+
+fun box(): String {
+    val sarr = arrayOf("OK")
+    val sarr2 = copyArray(*sarr)
+    sarr[0] = "Array was not copied"
+    assertEquals(sarr2[0], "OK", "Failed: Array<String>")
+
+    var rsarr = arrayOf("OK")
+    var rsarr2 = reifiedCopyArray(*rsarr)
+    rsarr[0] = "Array was not copied"
+    assertEquals(rsarr2[0], "OK", "Failed: Array<String>, reified copy")
+
+    val iarr = IntArray(1)
+    iarr[0] = 1
+    val iarr2 = copyIntArray(*iarr)
+    iarr[0] = 42
+    assertEquals(iarr2[0], 1, "Failed: IntArray")
+
+    return "OK"
+}