GDBserver disconnected tracing support.

* linux-low.c (linux_remove_process): Delete.
	(add_lwp): Don't set last_resume_kind here.
	(linux_kill): Use `mourn'.
	(linux_detach): Use `thread_db_detach', and `mourn'.
	(linux_mourn): New.
	(linux_attach_lwp_1): Adjust comment.
	(linux_attach): last_resume_kind moved the thread_info; adjust.
	(status_pending_p_callback): Adjust.
	(linux_wait_for_event_1): Adjust.
	(count_events_callback, select_singlestep_lwp_callback)
	(select_event_lwp_callback, cancel_breakpoints_callback)
	(db_wants_lwp_stopped, linux_wait_1, need_step_over_p)
	(proceed_one_lwp): Adjust.
	(linux_async): Add debug output.
	(linux_thread_stopped): New.
	(linux_pause_all): New.
	(linux_target_ops): Install linux_mourn, linux_thread_stopped and
	linux_pause_all.
	* linux-low.h (struct lwp_info): Delete last_resume_kind field.
	(thread_db_free): Delete declaration.
	(thread_db_detach, thread_db_mourn): Declare.
	* thread-db.c (thread_db_init): Use thread_db_mourn.
	(thread_db_free): Delete, split in two.
	(disable_thread_event_reporting): New.
	(thread_db_detach): New.
	(thread_db_mourn): New.

	* server.h (struct thread_info) <last_resume_kind>: New field.
	<attached>: Add comment.
	<gdb_detached>: New field.
	(handler_func): Change return type to int.
	(handle_serial_event, handle_target_event): Ditto.
	(gdb_connected): Declare.
	(tracing): Delete.
	(disconnected_tracing): Declare.
	(stop_tracing): Declare.

	* server.c (handle_query) <qSupported>: Report support for
	disconnected tracing.
	(queue_stop_reply_callback): Account for running threads.
	(gdb_wants_thread_stopped): New.
	(gdb_wants_all_threads_stopped): New.
	(gdb_reattached_process): New.
	(handle_status): Clear the `gdb_detached' flag of all processes.
	In all-stop, stop all threads.
	(main): Be sure to leave tfind mode.  Handle disconnected tracing.
	(process_serial_event): If the remote connection breaks, or if an
	exit was forced with "monitor exit", force an event loop exit.
	Handle disconnected tracing on detach.
	(handle_serial_event): Adjust.
	(handle_target_event): If GDB isn't connected, forward events back
	to the inferior, unless the last process exited, in which case,
	exit gdbserver.  Adjust interface.

	* remote-utils.c (remote_open): Don't block in accept.  Instead
	register an event loop source on the listen socket file
	descriptor.  Refactor bits into ...
	(listen_desc): ... this new global.
	(gdb_connected): ... this new function.
	(enable_async_notification): ... this new function.
	(handle_accept_event): ... this new function.
	(remote_close): Clear remote_desc.

	* inferiors.c (add_thread): Set the new thread's last_resume_kind.

	* target.h (struct target_ops) <mourn, thread_stopped, pause_all>:
	New fields.
	(mourn_inferior): Define.
	(target_process_qsupported): Avoid the dangling else problem.
	(thread_stopped): Define.
	(pause_all): Define.
	(target_waitstatus_to_string): Declare.
	* target.c (target_waitstatus_to_string): New.

	* tracepoint.c (tracing): Make extern.
	(disconnected_tracing): New.
	(stop_tracing): Make extern.  Handle tracing stops due to GDB
	disconnecting.
	(cmd_qtdisconnected): New.
	(cmd_qtstatus): Report disconnected tracing status in trace reply.
	(handle_tracepoint_general_set): Handle QTDisconnected.

	* event-loop.c (event_handler_func): Change return type to int.
	(process_event): Bail out if the event handler wants the event
	loop to stop.
	(handle_file_event): Ditto.
	(start_event_loop): Bail out if the event handler wants the event
	loop to stop.

	* nto-low.c (nto_target_ops): Adjust.
	* spu-low.c (spu_wait): Don't remove the process here.
	(spu_target_ops): Adjust.
	* win32-low.c (win32_wait): Don't remove the process here.
	(win32_target_ops): Adjust.

gdb/gdbserver/event-loop.c

@@ -39,7 +39,7 @@
 #endif
 
 typedef struct gdb_event gdb_event;
-typedef void (event_handler_func) (int);
+typedef int (event_handler_func) (int);
 
 /* Tell create_file_handler what events we are interested in.  */
 
@@ -211,7 +211,8 @@ process_event (void)
       free (event_ptr);
 
       /* Now call the procedure associated with the event.  */
-      (*proc) (fd);
+      if ((*proc) (fd))
+	return -1;
       return 1;
     }
 
@@ -347,7 +348,7 @@ delete_file_handler (int fd)
    through event_ptr->proc.  EVENT_FILE_DESC is file descriptor of the
    event in the front of the event queue.  */
 
-static void
+static int
 handle_file_event (int event_file_desc)
 {
   file_handler *file_ptr;
@@ -378,10 +379,16 @@ handle_file_event (int event_file_desc)
 
 	  /* If there was a match, then call the handler.  */
 	  if (mask != 0)
-	    (*file_ptr->proc) (file_ptr->error, file_ptr->client_data);
+	    {
+	      if ((*file_ptr->proc) (file_ptr->error,
+				     file_ptr->client_data) < 0)
+		return -1;
+	    }
 	  break;
 	}
     }
+
+  return 0;
 }
 
 /* Create a file event, to be enqueued in the event queue for
@@ -491,7 +498,13 @@ start_event_loop (void)
   while (1)
     {
       /* Any events already waiting in the queue?  */
-      if (process_event ())
+      int res = process_event ();
+
+      /* Did the event handler want the event loop to stop?  */
+      if (res == -1)
+	return;
+
+      if (res)
 	continue;
 
       /* Wait for a new event.  If wait_for_event returns -1, we