vquic: fix `-Wunused-parameter` with proxies disabled

Fixing:
```
lib/vquic/vquic.c:864:56: error: unused parameter 'conn' [-Werror,-Wunused-parameter]
  864 |                              const struct connectdata *conn,
      |                                                        ^
```

Closes #22104

diff --git a/lib/vquic/vquic.c b/lib/vquic/vquic.c
index 8cd006bcb5de106b9d8dd653641873d0a037e099..dfb8346c1ad340e57a4a789107c579aa9b283314 100644 (file)
--- a/lib/vquic/vquic.c
+++ b/lib/vquic/vquic.c
@@ -877,6 +877,8 @@ CURLcode Curl_conn_may_http3(struct Curl_easy *data,
     failf(data, "HTTP/3 is not supported over a SOCKS proxy");
     return CURLE_URL_MALFORMAT;
   }
+#else
+  (void)conn;
 #endif
 
   return CURLE_OK;