* Allow up to 10 whitespace separated arguments to user defined

    * Allow up to 10 whitespace separated arguments to user defined
        commands.
        * top.c (struct user_args): Structure for holding arguments to
        user defined commands.
        (print_command_line): Delete unused "tmp_chain" variable.  Clean
        up flow control by having cases exit in the same manner.
        Before executing a command or evaluating an expression, substitute
        the current $arg0..$arg9 values if the command/expression uses them.
        (arg_cleanup): New function.
        (setup_user_args, locate_arg, insert_args): Likewise.
        (execute_user_command): Allow arguments to user defined commands.

        * Allow if/while commands to be used within a breakpoint command
        list.
        * breakpoint.c (bpstat_do_actions): Call execute_control_command
        rather than execute_command (passes entire command structure rather
        than just the command line text).
        (breakpoint_1): Use "print_command_line" to print a breakpoint
        command line (including control structures).
        * gdbcmd.h (execute_control_command): Provide extern decl.
        (print_command_line): Likewise.
        * top.c (execute_control_command): No longer static.
        (print_command_line): New function to recursively print a command
        line, including control structures.