lavf/http: fix compilation without zlib

Regression since e2f8f14052.

libavformat/http.c

@@ -1248,7 +1248,9 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
     s->willclose        = 0;
     s->end_chunked_post = 0;
     s->end_header       = 0;
+#if CONFIG_ZLIB
     s->compressed       = 0;
+#endif
     if (post && !s->post_data && !send_expect_100) {
         /* Pretend that it did work. We didn't read any header yet, since
          * we've still to send the POST data, but the code calling this