Fixes direct messages falsely being shown as able to be boosted.

app/src/main/java/com/keylesspalace/tusky/StatusViewHolder.java

@@ -382,7 +382,7 @@ class StatusViewHolder extends RecyclerView.ViewHolder {
             hideSensitiveMediaWarning();
         }
         setupButtons(listener, realStatus.account.id);
-        setRebloggingEnabled(realStatus.visibility != Status.Visibility.PRIVATE);
+        setRebloggingEnabled(status.rebloggingAllowed());
         if (realStatus.spoilerText.isEmpty()) {
             hideSpoilerText();
         } else {

app/src/main/java/com/keylesspalace/tusky/entity/Status.java

@@ -47,12 +47,15 @@ public class Status {
     }
 
     public enum Visibility {
+        UNKNOWN,
         @SerializedName("public")
         PUBLIC,
         @SerializedName("unlisted")
         UNLISTED,
         @SerializedName("private")
         PRIVATE,
+        @SerializedName("direct")
+        DIRECT,
     }
 
     public String id;
@@ -81,6 +84,13 @@ public class Status {
         return visibility == null ? Visibility.UNLISTED : visibility;
     }
 
+    public boolean rebloggingAllowed() {
+        return visibility != null
+                && visibility != Visibility.PRIVATE
+                && visibility != Visibility.DIRECT
+                && visibility != Visibility.UNKNOWN;
+    }
+
     @SerializedName("media_attachments")
     public MediaAttachment[] attachments;