Remove TCPIP_CMD_FATAL_ERROR_REQ

When the TCPIP_CMD_FATAL_ERROR_REQ is sent to the TCP/IP stack, this will lead to a situation where the stack ends up in an endless loop.

This can be triggered by sending this entry e.g. over the TCP/IP marshaller, so this is a potential security hazard and shall be removed.

In addition there is a second mechanisem that works totally internally which can be used instead.