Use tor_socket_t, not unsigned, in tor-fw-helper-natmp.c

changes/bug1983_win64

+  o Minor bugfixes
+    - Use an appropriate-width type for sockets in tor-fw-helper on
+      win664. Fixes bug 1983 at last. Bugfix on 0.2.3.9-alpha.

src/tools/tor-fw-helper/tor-fw-helper-natpmp.c

@@ -87,7 +87,7 @@ tor_natpmp_cleanup(tor_fw_options_t *tor_fw_options, void *backend_state)
 
 /** Use select() to wait until we can read on fd. */
 static int
-wait_until_fd_readable(unsigned int fd, struct timeval *timeout)
+wait_until_fd_readable(tor_socket_t fd, struct timeval *timeout)
 {
   int r;
   fd_set fds;