how to identify excess includes

edit savecancel

Does your IDE or editor of choice not show errors when it cannot find a header? If it does, why not just delete the suspects and check whether it still compiles?

You could run a command on the command line, prepending #warning "I am being included" or some such thing to every header, although that seems not so straightforward, so you might be better off inserting that line by hand. The #warning directive prints something when the header is processed, so you should see al those messages belonging to included headers.