gdb/doc:

gdb/doc:

	* observer.texi (GDB Observers): New observer 'traceframe_changed'.
	* gdb.texinfo (GDB/MI Async Records): Mention new MI notification
	'=traceframe-changed'.

gdb:

	* tracepoint.c (tfind_1): Call observer_notify_traceframe_changed
	if traceframe changed.

	* mi/mi-cmds.c (mi_cmd mi_cmds): Adjust for command
	"trace-find".
	* mi/mi-interp.c: Declare 'mi_traceframe_changed'.
	(mi_interpreter_init): Hook mi_traceframe_changed to observer
	'traceframe_changed'.
	(mi_traceframe_changed): New.
	* mi/mi-main.h (struct mi_suppress_notification) <traceframe>:
	New field.

	* NEWS: Mention the new MI notification.

gdb/testsuite:

	* gdb.trace/mi-traceframe-changed.exp: New.