Replace struct continuation_args by void* and per command structs.

	Replace struct continuation_args by void* and per command structs.

	* top.c (execute_command): Remove unused arg1 and arg2 locals.

	* breakpoint.c (struct until_break_command_continuation_args):
	New.
	(until_break_command_continuation): Take a void* instead of a
	continuations_arg.  Adjust.
	(until_break_command): Adjust to use struct
	until_break_command_continuation_args instead of struct
	continuation_arg.

	* infcmd.c (struct step_1_continuation_args): New.
	(step_1_continuation): Take a void* instead of a
	continuations_arg.  Adjust to use struct step_1_continuation_args.
	(step_once): Adjust to use struct step_1_continuation_args.

	(struct finish_command_continuation_args): New.
	(finish_command_continuation): Take a void* instead of a
	continuations_arg.  Adjust to use struct
	finish_command_continuation_args.
	(finish_command): Adjust to use struct
	finish_command_continuation_args.
	(struct attach_command_continuation_args): New.
	(attach_command_continuation): Take a void* instead of a
	continuations_arg.  Adjust to use struct
	attach_command_continuation_args.
	(attach_command): Adjust to use struct
	attach_command_continuation_args.

	* defs.h (struct continuation_arg): Delete.
	(struct continuation): Replace the struct continuation_arg*
	parameter of continuation_hook by a void*.  Replace "arg_list"
	member by a new "args" member with void* type.
	(add_continuation, add_intermediate_continuation): Replace struct
	continuation_arg type usages by void* usages.

	* utils.c (add_continuation, do_all_continuations)
	(add_intermediate_continuation)
	(do_all_intermediate_continuations): Replace struct
	continuation_arg type usages by void* usages.  Pass "args" instead
	of "arg_list".