Option to disable internal socket API to use bypass mode and lwip stack

[SebastianFoerster]

The socket API of the stack has a lot dependency's in different files. There should be a define switch to disable the socket API if only the raw bypass mode is used and a own TCP/IP Stack like lwip.

A concrete problem was the SO_RCVTIMEO define that use 20 at rs9116 stack instead of lwips 0x1006.

best regards

sebastian