BSD-style lwIP TCP/IP stack support:

Allow compilation of libcurl and curl using BSD-style lwIP on Win32.

In order to compile libcurl and curl with this support it is necessary
to edit files lib/config-win32.h and src/config-win32.h and uncomment
a line to make definition of preprocessor symbol USE_LWIPSOCK visible.

Afterwards you can compile as usual.

In order to use compiled library with BSD-style lwIP TCP/IP stack in
your program it is mandatory that you include lwIP header file <lwip/opt.h>
before including <curl/curl.h> or <curl/multi.h>

Compilation has been verified with lwIP 1.4.0 and contrib-1.4.0 from:

http://download.savannah.gnu.org/releases/lwip/lwip-1.4.0.zip
http://download.savannah.gnu.org/releases/lwip/contrib-1.4.0.zip

Have fun!