Define HAVE_WINDNS and NO_LIMIT_FD_SETSIZE

HAVE_WINDNS is defined when we want to use DNSAPI on Windows which
handles most of the resolver work for us.

NO_LIMIT_FD_SETSIZE is defined if the value of a socket FD does not
imply anything about the number of sockets so far assigned.
I.e. checking if the socket is larger than FD_SETSIZE is incorrect.

include/config.h.w32

@@ -1224,6 +1224,9 @@ static const char *const rcsid[] = { (const char *)rcsid, "@(#)" msg }
 /* Defined if we have WinSock */
 #define HAVE_WINSOCK 1
 
+/* Defined if we have WinDNS */
+#define HAVE_WINDNS 1
+
 /* define if struct winsize has ws_xpixel */
 /* #define HAVE_WS_XPIXEL 1 */
 
@@ -1404,6 +1407,9 @@ static const char *const rcsid[] = { (const char *)rcsid, "@(#)" msg }
 /* Define if a socket is not a file descriptor */
 #define SOCKET_IS_NOT_AN_FD 1
 
+/* Define if FD_SETSIZE check does not apply to this platform */
+#define NO_LIMIT_FD_SETSIZE 1
+
 /* Define to 1 if you have the ANSI C header files. */
 #define STDC_HEADERS 1