Lwip translator updates for working with lwip 2.0.3

[Joan Lledó]

I've got two patches for the lwip translator.

The first patch only creates a new config.h file in the lwip/ folder. I'm not 
sure whether this is really required (should config.h be generated?) but I 
cannot compile the translator without it. So just ignore it if this is only my 
problem.

The second patch is required for working with lwip 2.0.3. I added a new macro 
in liblwip 2.0.3 which allows switching between using POSIX or lwip socket 
headers when building the library. This requires the translator to add some 
#includes.

> For instance, or to debian-hurd@lists.debian.org

OK, I'm sending the debian pkg patches there