multi: fix compiler warning with `CURL_DISABLE_WAKEUP`

`use_wakeup` is unused in this case.

Closes https://github.com/curl/curl/pull/7661

diff --git a/lib/multi.c b/lib/multi.c
index 82d538d009e3cbbfe9bfebaaccabeaa0c17dd1de..85097816db5937e8a1dc484cd32be0462354fb1b 100644 (file)
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -1100,6 +1100,9 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
   WSANETWORKEVENTS wsa_events;
   DEBUGASSERT(multi->wsa_event != WSA_INVALID_EVENT);
 #endif
+#ifndef ENABLE_WAKEUP
+  (void)use_wakeup;
+#endif
 
   if(!GOOD_MULTI_HANDLE(multi))
     return CURLM_BAD_HANDLE;