Handle unexpected null cursor and don't forget to close it.

Bug: 5406071
Change-Id: Ia40cf7e5a3e32d6f364e787ee66580c685507571

src/com/android/settings/SoundSettings.java

@@ -351,9 +351,12 @@ public class SoundSettings extends SettingsPreferenceFragment implements
             try {
                 Cursor cursor = context.getContentResolver().query(ringtoneUri,
                         new String[] { MediaStore.Audio.Media.TITLE }, null, null, null);
+                if (cursor != null) {
                     if (cursor.moveToFirst()) {
                         summary = cursor.getString(0);
                     }
+                    cursor.close();
+                }
             } catch (SQLiteException sqle) {
                 // Unknown title for the ringtone
             }