[libcontacts] Ensure BT contacts are found for import merge

When merging imported contacts into the existing data set, ensure that
contacts with 'bluetooth' syncTarget values are considered as potential
merge candidates.

src/seasideimport.cpp

@@ -94,7 +94,7 @@ QContactFilter localContactFilter()
     filterWasLocal.setValue(QString::fromLatin1("was_local"));
     filterBluetooth.setValue(QString::fromLatin1("bluetooth"));
 
-    return filterLocal | filterWasLocal;
+    return filterLocal | filterWasLocal | filterBluetooth;
 }
 
 bool nameIsEmpty(const QContactName &name)