CppEditor: Updating local uses before matching quick fixes

This is necessary since invoking the context menu changes the cursor
position, on which the local uses and some refactoring actions depend.

Change-Id: I32563085bfb106f754992704e569915b9ee5b127
Task-number: QTCREATORBUG-13388
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>