Only mark as read voicemails with the "is_read" flag set.

The vvm sync service was querying for all voicemails with the "dirty"
bit set instead of voicemails that had actually been read and then
marking the voicemail as "read" locally. This resulted in voicemails
being marked as read that had not been listened to by the user.

Bug: 23351142
Change-Id: I24500fca0e835f643b3c635d498f51947359a481
diff --git a/src/com/android/phone/vvm/omtp/sync/VoicemailsQueryHelper.java b/src/com/android/phone/vvm/omtp/sync/VoicemailsQueryHelper.java
index b86351c..8e2c76a 100644
--- a/src/com/android/phone/vvm/omtp/sync/VoicemailsQueryHelper.java
+++ b/src/com/android/phone/vvm/omtp/sync/VoicemailsQueryHelper.java
@@ -48,7 +48,8 @@
     public static final int IS_READ = 2;
     public static final int DELETED = 3;
 
-    final static String READ_SELECTION = Voicemails.DIRTY + "=1 AND " + Voicemails.DELETED + "!=1";
+    final static String READ_SELECTION = Voicemails.DIRTY + "=1 AND "
+                + Voicemails.DELETED + "!=1 AND " + Voicemails.IS_READ + "=1";
     final static String DELETED_SELECTION = Voicemails.DELETED + "=1";
 
     private Context mContext;