Use Intrinsics#compare when specializing compareTo for ints

compiler/testData/codegen/bytecodeText/boxingOptimization/intCompareTo.kt

@@ -0,0 +1,11 @@
+fun box(): String {
+    val a: Any = 1
+    val b: Any = 42
+    val test = (a as Comparable<Any>).compareTo(b)
+    if (test != -1) return "Fail: $test"
+
+    return "OK"
+}
+
+// 0 compareTo
+// 1 Intrinsics.compare