Avoid warning on empty expressions

For some reason, Q_UNUSED includes already a semicolon, adding one
on the user side creates an additional empty statement.

Change-Id: I9c5e8fac381345a60792cb75e2938fd53958d3b0
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/cpaster/pastecodedotxyzprotocol.cpp

@@ -86,7 +86,7 @@ void PasteCodeDotXyzProtocol::paste(const QString &text, Protocol::ContentType c
         return QByteArray(); // Crutch for compiler.
     };
     data += "&lang=" + langValue(ct);
-    Q_UNUSED(comment);
+    Q_UNUSED(comment)
 
     QNetworkReply * const reply = httpPost(apiUrl() + "/create", data);
     connect(reply, &QNetworkReply::finished, this, [this, reply] {