tcp: Explicitly convert a pointer to a boolean integer

This fixes warnings about making integers from pointers without
a cast, and avoids the theoretical case where the lower 32 bits of
the pointer would all be zero where the implicit cast wouldn't give
the right result.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/tcp.c

@@ -100,7 +100,7 @@ static int tcp_open(URLContext *h, const char *uri, int flags)
         }
     } else {
         if ((ret = ff_listen_connect(fd, cur_ai->ai_addr, cur_ai->ai_addrlen,
-                                     timeout * 100, h, cur_ai->ai_next)) < 0) {
+                                     timeout * 100, h, !!cur_ai->ai_next)) < 0) {
 
             if (ret == AVERROR_EXIT)
                 goto fail1;