* inferior.h (context_switch_to): Delete.

	* inferior.h (context_switch_to): Delete.
	* infrun.c (context_switch): Don't save and load infrun state.
	(context_switch_to): Delete.

	* infcmd.c (proceed_thread_callback): Replace context_switch_to
	calls by switch_to_thread calls.

	* gdbthread.h (save_infrun_state, load_infrun_state): Delete.
	* thread.c (main_thread_state, main_thread_executing): Delete.
	(inferior_thread): Delete references to them.
	(add_thread_silent): Fix case where we're adding a thread with the
	same ptid as an exited thread.  Remove references to
	context-switching.
	(load_infrun_state, save_infrun_state): Delete.
	(thread_alive, is_thread_state, any_running, is_executing)
	(set_executing): Remove the special handling for targets that
	don't register any thread.
	(restore_current_thread, thread_apply_all_command)
	(do_captured_thread_select): Unconditionally call
	switch_to_thread.

	* mi/mi-main.c (mi_cmd_execute): Check for exited threads.
	Call switch_to_thread instead of context_switch_to.