Use Long.compare to compare longs

Fix potential int overflow in comparator.

Bug:24117229
Change-Id: I8095e19ff9b853dcf3530e1cabd8dc9d8e326b0a
diff --git a/src/com/android/contacts/editor/RawContactDeltaComparator.java b/src/com/android/contacts/editor/RawContactDeltaComparator.java
index 17a4dda..1a00c9d 100644
--- a/src/com/android/contacts/editor/RawContactDeltaComparator.java
+++ b/src/com/android/contacts/editor/RawContactDeltaComparator.java
@@ -120,12 +120,14 @@
         // Both are in the same account, fall back to contact ID
         Long oneId = one.getRawContactId();
         Long twoId = two.getRawContactId();
-        if (oneId == null) {
+        if (oneId == null && twoId == null) {
+            return 0;
+        } else if (oneId == null) {
             return -1;
         } else if (twoId == null) {
             return 1;
         }
 
-        return (int) (oneId - twoId);
+        return Long.compare(oneId, twoId);
     }
-}
\ No newline at end of file
+}