Move comparison related functions to kotlin.comparisons, update imports in stdlib.

libraries/stdlib/test/collections/SequenceTest.kt

@@ -4,6 +4,7 @@ import org.junit.Test as test
 import org.junit.Test
 import kotlin.test.*
 import java.util.*
+import kotlin.comparisons.*
 
 fun fibonacci(): Sequence<Int> {
     // fibonacci terms