Fix NPE in Utils.matrixCursorFromCursor().

Bug: 6145376
Change-Id: I91f50431fa9311f64608cdc0438efe5b7b598ae4
diff --git a/src/com/android/calendar/Utils.java b/src/com/android/calendar/Utils.java
index 5324551..c8944d8 100644
--- a/src/com/android/calendar/Utils.java
+++ b/src/com/android/calendar/Utils.java
@@ -285,7 +285,11 @@
     }
 
     public static MatrixCursor matrixCursorFromCursor(Cursor cursor) {
-        MatrixCursor newCursor = new MatrixCursor(cursor.getColumnNames());
+        String[] columnNames = cursor.getColumnNames();
+        if (columnNames == null) {
+            columnNames = new String[] {};
+        }
+        MatrixCursor newCursor = new MatrixCursor(columnNames);
         int numColumns = cursor.getColumnCount();
         String data[] = new String[numColumns];
         cursor.moveToPosition(-1);