gdb/gdbserver/

gdb/gdbserver/
	PR remote/14161.

	* server.h: Declare gdb_agent_about_to_close.
	* target.c (kill_inferior): Include "agent.h".
	New.  Send command 'kill'.
	* target.h (kill_inferior): Removed macro.
	* tracepoint.c (gdb_agent_about_to_close): New.
	(gdb_agent_helper_thread): Handle command 'close'.
	Wait endlessly until the inferior stops.
	Install gdb_agent_remove_socket to atexit hook.
	(agent_socket_name): New static variable.
	(gdb_agent_socket_init): Replace local variable 'name' with
	'agent_socket_name'.
	(gdb_agent_remove_socket): New.

gdb/doc/
	* gdb.texinfo (IPA Protocol Commands): Document new command
	'close'.

gdb/testsuite/
	KFAIL for PR remote/14161.
	* gdb.trace/strace.exp (strace_remove_socket): kfail for native.
	Cleanup socket files.
	(strace_info_marker): Detach inferior.