Define winnt or greater on mingw32 to take advantage of get*info().

src/listen.c

@@ -35,6 +35,7 @@
 #include <assert.h>
 
 #ifdef WIN32
+#define WINVER 0x0501
 #include <ws2tcpip.h>
 #include <winsock.h>
 #else

src/socket_util.c

@@ -28,6 +28,7 @@
 #include <sys/socket.h>
 #include <netdb.h>
 #else /* G_OS_WIN32 */
+#define WINVER 0x0501
 #include <ws2tcpip.h>
 #include <winsock.h>
 #endif /* G_OS_WIN32 */