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/coreplugin/variablechooser.cpp

@@ -466,7 +466,7 @@ void VariableChooserPrivate::updateButtonGeometry()
 
 void VariableChooserPrivate::updateCurrentEditor(QWidget *old, QWidget *widget)
 {
-    Q_UNUSED(old);
+    Q_UNUSED(old)
     if (!widget) // we might loose focus, but then keep the previous state
         return;
     // prevent children of the chooser itself, and limit to children of chooser's parent