Fix warning for -no-feature-multiprocess

Change-Id: Ifa3382098c8f7c2cb1750b7ac5e583ddd71895e2
Reviewed-by: Stephan Binner <stephan.binner@basyskom.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/platformsupport/services/genericunix/qgenericunixservices.cpp

@@ -168,12 +168,14 @@ QByteArray QGenericUnixServices::desktopEnvironment() const
 
 bool QGenericUnixServices::openUrl(const QUrl &url)
 {
+    Q_UNUSED(url)
     qWarning("openUrl() not supported on this platform");
     return false;
 }
 
 bool QGenericUnixServices::openDocument(const QUrl &url)
 {
+    Q_UNUSED(url)
     qWarning("openDocument() not supported on this platform");
     return false;
 }