as much as possible:
* dtable.cc: Drop including sys/socket.h.
* fhandler_procnet.cc: Change includes accordingly.
* fhandler_socket.cc: Ditto.
(fhandler_socket::listen): Avoid gcc error message initializing sin6.
(LPFN_WSARECVMSG): Only define when building against w32api headers.
* net.cc: Change includes accordingly. Define USE_SYS_TYPES_FD_SET
and __WSA_ERR_MACROS_DEFINED. Define _INC_NETIOAPI temporarily and
explain why.
(struct _IP_ADAPTER_UNICAST_ADDRESS_LH): Only define when building
against w32api headers.
(struct _IP_ADAPTER_ADDRESSES_LH): Ditto.
(SIO_GET_INTERFACE_LIST): Ditto.
(ws_freeaddrinfo): Rename from freeaddrinfo so as not to collide with
Winsock declaration. Change througout.
(ws_getaddrinfo): Ditto.
(ws_getnameinfo): Ditto.
* select.cc: Include netdb.h after defining USE_SYS_TYPES_FD_SET.
* syslog.cc: Drop including netinet/in.h. Define USE_SYS_TYPES_FD_SET
and include ws2tcpip.h.
* include/netdb.h (struct addrinfo): Don't define when building Cygwin.
* include/cygwin/if.h: Don't declare if_xxx functions when building
Cygwin.
* include/cygwin/in.h: Disable most definitions when building Cygwin.
* include/cygwin/socket.h: Disable sockaddr and sockaddr_storage
definitions when building Cygwin. Same for MCAST_INCLUDE/MCAST_EXCLUDE.
* libc/inet_addr.c: Don't define __INSIDE_CYGWIN__ nor
__INSIDE_CYGWIN_NET__.
* libc/inet_network.c: Ditto.
* libc/minires.h: Drop redundant inclusion of netdb.h. Define
__INSIDE_CYGWIN_NET__ only before including netdb.h and resolver
headers.
