* tracepoint.c (TFILE_PID): Remove.
(tfile_open): Don't add thread and inferior.
(tfile_close): Don't set 'inferior_ptid'. Don't call
exit_inferior_silent.
(tfile_thread_alive): Remove.
(init_tfile_ops): Don't set field 'to_thread_alive' of
tfile_ops.
gdb/testsuite/
* gdb.trace/tfile.exp: Test inferior and thread.