removed unnecessary unboxing followed by reboxing

Since id is a Long, Long.valueOf(long) unboxed the Long to a primitive
long, then reboxed it into a Long instance, which was again unboxed to
allow it to be set as an element of the array of longs. This commit
reduces the number of boxings from 3 to 1.

src/com/fsck/k9/fragment/MessageListFragment.java

@@ -895,7 +895,7 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
         long[] selected = new long[mSelected.size()];
         int i = 0;
         for (Long id : mSelected) {
-            selected[i++] = Long.valueOf(id);
+            selected[i++] = id;
         }
         outState.putLongArray(STATE_SELECTED_MESSAGES, selected);
     }