Fixing NPE during selection of synced calendars.

If the connection is slow, and the accounts cursor has not finished
the query before onStop() of SelectSyncedCalendarsMultiAccountActivity
is called, we can have a NPE on the accounts cursor.

Bug: 7742419
Change-Id: I48f4b7ce0236a63c5b5c0e9665dad90c5a8d21da

src/com/android/calendar/selectcalendars/SelectSyncedCalendarsMultiAccountActivity.java

@@ -110,7 +110,7 @@ protected void onPause() {
     protected void onStop() {
         super.onStop();
         mAdapter.closeChildrenCursors();
-        if (!mAccountsCursor.isClosed()) {
+        if (mAccountsCursor != null && !mAccountsCursor.isClosed()) {
             mAccountsCursor.close();
         }
     }