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/languageclient/client.cpp

@@ -772,7 +772,7 @@ void Client::handleCodeActionResponse(const CodeActionRequest::Response &respons
                 if (auto action = Utils::get_if<CodeAction>(&item))
                     updateCodeActionRefactoringMarker(this, *action, uri);
                 else if (auto command = Utils::get_if<Command>(&item)) {
-                    Q_UNUSED(command); // todo
+                    Q_UNUSED(command) // todo
                 }
             }
         }