event/SocketMonitor: don't close the socket automatically

Users now have to call Close() explicitly.  This simplifies using the
class, as most users have automatic socket management already, and
Steal() had to be used often.

src/AvahiPoll.cxx

@@ -57,10 +57,6 @@ public:
 		Schedule(FromAvahiWatchEvent(_event));
 	}
 
-	~AvahiWatch() {
-		Steal();
-	}
-
 	static void WatchUpdate(AvahiWatch *w, AvahiWatchEvent event) {
 		w->Schedule(FromAvahiWatchEvent(event));
 	}

src/Client.hxx

@@ -82,6 +82,11 @@ public:
 	Client(EventLoop &loop, Partition &partition,
 	       int fd, int uid, int num);
 
+	~Client() {
+		if (FullyBufferedSocket::IsDefined())
+			FullyBufferedSocket::Close();
+	}
+
 	bool IsConnected() const {
 		return FullyBufferedSocket::IsDefined();
 	}

src/InotifySource.hxx

@@ -38,6 +38,10 @@ class InotifySource final : private SocketMonitor {
 		      mpd_inotify_callback_t callback, void *ctx, int fd);
 
 public:
+	~InotifySource() {
+		Close();
+	}
+
 	/**
 	 * Creates a new inotify source and registers it in the GLib main
 	 * loop.

src/ZeroconfBonjour.cxx

@@ -43,7 +43,6 @@ public:
 	}
 
 	~BonjourMonitor() {
-		Steal();
 		DNSServiceRefDeallocate(service_ref);
 	}
 

src/event/Loop.cxx

@@ -42,9 +42,6 @@ EventLoop::~EventLoop()
 {
 	assert(idle.empty());
 	assert(timers.empty());
-
-	/* avoid closing the WakeFD twice */
-	SocketMonitor::Steal();
 }
 
 void

src/event/MultiSocketMonitor.hxx

@@ -143,7 +143,6 @@ public:
 				i->SetEvents(events);
 				prev = i;
 			} else {
-				i->Steal();
 				fds.erase_after(prev);
 			}
 		}

src/event/ServerSocket.cxx

@@ -90,6 +90,9 @@ public:
 
 	~OneServerSocket() {
 		g_free(address);
+
+		if (IsDefined())
+			Close();
 	}
 
 	unsigned GetSerial() const {

src/event/SignalMonitor.cxx

@@ -58,14 +58,6 @@ public:
 #endif
 	}
 
-	~SignalMonitor() {
-		/* prevent the descriptor to be closed twice */
-#ifdef USE_SIGNALFD
-		if (SocketMonitor::IsDefined())
-#endif
-			SocketMonitor::Steal();
-	}
-
 	using SocketMonitor::GetEventLoop;
 
 #ifdef USE_SIGNALFD

src/event/SocketMonitor.cxx

@@ -43,7 +43,7 @@ SocketMonitor::Dispatch(unsigned flags)
 SocketMonitor::~SocketMonitor()
 {
 	if (IsDefined())
-		Close();
+		Cancel();
 }
 
 void

src/event/SocketMonitor.hxx

@@ -44,6 +44,9 @@ class EventLoop;
  * #EventLoop will invoke virtual method OnSocketReady() as soon as
  * any of the subscribed events are ready.
  *
+ * This class does not feel responsible for closing the socket.  Call
+ * Close() to do it manually.
+ *
  * This class is not thread-safe, all methods must be called from the
  * thread that runs the #EventLoop, except where explicitly documented
  * as thread-safe.
@@ -91,7 +94,7 @@ public:
 
 	/**
 	 * "Steal" the socket descriptor.  This abandons the socket
-	 * and puts the responsibility for closing it to the caller.
+	 * and returns it.
 	 */
 	int Steal();
 

src/input/CurlInputPlugin.cxx

@@ -200,8 +200,6 @@ public:
 		   Abandon() would be most appropriate, but it breaks
 		   the second case - is that a CURL bug?  is there a
 		   better solution? */
-
-		Steal();
 	}
 
 	/**

src/output/HttpdClient.cxx

@@ -42,6 +42,9 @@ HttpdClient::~HttpdClient()
 
 	if (metadata)
 		metadata->Unref();
+
+	if (IsDefined())
+		BufferedSocket::Close();
 }
 
 void