Replace Long.compare() with implementation.

- Long.compare() was added in API level 19.

Change-Id: Ic7020c941403c10daa6feacdc737c6a82676ada0
diff --git a/src/com/android/launcher3/Utilities.java b/src/com/android/launcher3/Utilities.java
index d054da3..2ed9a25 100644
--- a/src/com/android/launcher3/Utilities.java
+++ b/src/com/android/launcher3/Utilities.java
@@ -747,4 +747,11 @@
             return msg;
         }
     }
+
+    /**
+     * Replacement for Long.compare() which was added in API level 19.
+     */
+    public static int longCompare(long lhs, long rhs) {
+        return lhs < rhs ? -1 : (lhs == rhs ? 0 : 1);
+    }
 }