Merge pull request #12737 from NixOS/mergify/bp/2.24-maintenance/pr-12736

`MonitorFdHup::~MonitorFdHup`: use proper close method instead of lib… (backport #12736)

src/libutil/unix/monitor-fd.hh

@@ -122,7 +122,7 @@ public:
 
     ~MonitorFdHup()
     {
-        close(notifyPipe.writeSide.get());
+        notifyPipe.writeSide.close();
         thread.join();
     }
 };