ws2tcpip.h include bug

[Ozkan Sezer]

Hello:

The config header checks for windows' ws2tcpip.h have a little bug where
they do not include winsock2.h before ws2tcpip.h: ws2tcpip.h requires
winsock2.h to be included before, a plain AC_CHECK_HEADERS([ws2tcpip.h])
like in current m4/sys_socket_h.m4 may fail to detect the header's
presence. A solution may be changing the CFLAGS temporarily by adding
"-include winsock2.h" to it.

Regards.

--
Ozkan