drivers/bus/tcpip.cxx does not compile after transition to C++ (fix in attachments)

[Lukas Gerritzen]

The tcpip bus driver does not compile. I made similar modifications to the other drivers to make it work. Since I do not have write access, I attached my version.

The bug is reproducible e. g. by modifying the slowcont example such that the frontend uses the tcpip bus driver.

[Stefan Ritt]

Thanks for the fix, committed.