Kernel: Unix domain sockets close can now be detected

When a unix domain socket is closed and it has a connection to another
socket, it will make the other socket readable and recv will return 0.

This allows detection of socket closing

kernel/include/kernel/Networking/UNIX/Socket.h

@@ -46,6 +46,7 @@ namespace Kernel
 		{
 			bool										listening { false };
 			BAN::Atomic<bool>							connection_done { false };
+			mutable BAN::Atomic<bool>					target_closed { false };
 			BAN::WeakPtr<UnixDomainSocket>				connection;
 			BAN::Queue<BAN::RefPtr<UnixDomainSocket>>	pending_connections;
 			Semaphore									pending_semaphore;