Avoid warning on certain debug builds.

The variable is used in the TRACE(), but that is only enabled for
DEBUG >= 2. This therefore avoids a warning on DEBUG=1 builds.

Inspired by patch in #8252 by Urias McCullough.

src/servers/media/NodeManager.cpp

@@ -254,6 +254,7 @@ NodeManager::ReleaseNodeReference(media_node_id id, team_id team)
 
 #if DEBUG
 	int32 teamCount = teamRef->second - 1;
+	(void)teamCount;
 #endif
 
 	if (--teamRef->second == 0)