ClangTools: Modernize

modernize-use-nullptr
modernize-use-override
modernize-use-equals-default

Change-Id: I14a840c6f2972f57763cdfd4bb4483df1ec261d4
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangtools/clangtoolruncontrol.cpp

@@ -354,7 +354,7 @@ void ClangToolRunControl::stop()
     QSetIterator<ClangToolRunner *> i(m_runners);
     while (i.hasNext()) {
         ClangToolRunner *runner = i.next();
-        QObject::disconnect(runner, 0, this, 0);
+        QObject::disconnect(runner, nullptr, this, nullptr);
         delete runner;
     }
     m_runners.clear();