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/server.h

@@ -179,6 +179,9 @@ struct thread_info
   void *target_data;
   void *regcache_data;
 
+  /* The last resume GDB requested on this thread.  */
+  enum resume_kind last_resume_kind;
+
   /* The last wait status reported for this thread.  */
   struct target_waitstatus last_status;
 
@@ -224,8 +227,14 @@ struct process_info
 {
   struct inferior_list_entry head;
 
+  /* Nonzero if this child process was attached rather than
+     spawned.  */
   int attached;
 
+  /* True if GDB asked us to detach from this process, but we remained
+     attached anyway.  */
+  int gdb_detached;
+
   /* The symbol cache.  */
   struct sym_cache *symbol_cache;
 
@@ -327,7 +336,7 @@ extern int non_stop;
 
 /* Functions from event-loop.c.  */
 typedef void *gdb_client_data;
-typedef void (handler_func) (int, gdb_client_data);
+typedef int (handler_func) (int, gdb_client_data);
 
 extern void delete_file_handler (int fd);
 extern void add_file_handler (int fd, handler_func *proc,
@@ -336,8 +345,8 @@ extern void add_file_handler (int fd, handler_func *proc,
 extern void start_event_loop (void);
 
 /* Functions from server.c.  */
-extern void handle_serial_event (int err, gdb_client_data client_data);
-extern void handle_target_event (int err, gdb_client_data client_data);
+extern int handle_serial_event (int err, gdb_client_data client_data);
+extern int handle_target_event (int err, gdb_client_data client_data);
 
 extern void push_event (ptid_t ptid, struct target_waitstatus *status);
 
@@ -354,6 +363,8 @@ extern int all_symbols_looked_up;
 extern int noack_mode;
 extern int transport_is_reliable;
 
+int gdb_connected (void);
+
 ptid_t read_ptid (char *buf, char **obuf);
 char *write_ptid (char *buf, ptid_t ptid);
 
@@ -499,6 +510,11 @@ char *phex_nz (ULONGEST l, int sizeof_l);
 
 void initialize_tracepoint (void);
 
+extern int tracing;
+extern int disconnected_tracing;
+
+void stop_tracing (void);
+
 int handle_tracepoint_general_set (char *own_buf);
 int handle_tracepoint_query (char *own_buf);