add new Anti-Feature: NoSourceSince

* https://f-droid.org/wiki/page/Antifeature:NoSourceSince
* fdroidserver!529
* fdroidserver#508

app/src/main/java/org/fdroid/fdroid/views/AppDetailsRecyclerViewAdapter.java

@@ -550,6 +550,8 @@ public class AppDetailsRecyclerViewAdapter
                     return itemView.getContext().getString(R.string.antidisabledalgorithmlist);
                 case "KnownVuln":
                     return itemView.getContext().getString(R.string.antiknownvulnlist);
+                case "NoSourceSince":
+                    return itemView.getContext().getString(R.string.antinosourcesince);
                 default:
                     return af;
             }

app/src/main/res/values/strings.xml

@@ -218,6 +218,7 @@ This often occurs with apps installed via Google Play or other sources, if they
     <string name="antinonfreeassetslist">This app contains non-free assets</string>
     <string name="antidisabledalgorithmlist">This app has a weak security signature</string>
     <string name="antiknownvulnlist">This app contains a known security vulnerability</string>
+    <string name="antinosourcesince">The source code is no longer available, no updates possible.</string>
 
     <string name="display">Display</string>