Add missing QHash

Summary:
Fixes build with future Frameworks.

In master, this should make 69c492a54b obsolete.

Reviewers: alexeymin, #kde_applications, lbeltrame

Reviewed By: alexeymin, #kde_applications, lbeltrame

Differential Revision: https://phabricator.kde.org/D23059

krfb/trayicon.h

@@ -18,6 +18,8 @@
 #ifndef TRAYICON_H
 #define TRAYICON_H
 
+#include <QHash>
+
 #include <KStatusNotifierItem>
 
 class RfbClient;