Implement -thread-info.

	Implement -thread-info.
        * gdbthread.h (print_thread_info): Declare.

        * thread.c (print_thread_info): New, extracted
        from info_threads_command and adjusted to
        work for CLI and MI.
        (info_threads_command): Use print_thread_info.
	* Makefile.in: Update dependencies.

        * mi/mi-cmds.c (mi_cmds): Specify a handler
        for -thread-info.
        * mi/mi-cmds.h (mi_cmd_thread_info): Declare.
        * mi/mi-main.c (mi_cmd_thread_info): New.
        (mi_cmd_list_features): Include 'thread-info'.