exec_cleanup murder.

	exec_cleanup murder.
	* breakpoint.c (until_break_command_continuation): Add
	the 'error' parameter.  Directly delete the breakoint as
	opposed to running cleanups.
	(until_break_command): Install continuation only
	after starting the target.  Don't use exec cleanups,
	use ordinary cleanups.  Discard cleanups is successfully
	started the target in async mode.
	(make_cleanup_delete_breakpoint): Remove.
	* breakpoint.h (make_cleanup_delete_breakpoint): Remove
	declaration.
	* defs.h (do_exec_cleanups, make_exec_cleanup): Remove
	declarations.
	(struct continations): Add the 'error' parameter to the
	continuation_hook field.
	(add_continuation, do_all_continuations)
	(add_intermediate_continuation)
	(do_all_intermediate_continuations): Add the 'error' parameter.
	* exceptions.c (throw_exception): Don't call do_exec_cleanups.
	* inf-loop.c (inferior_event_handler): Instead of calling
	discard_all_continuations, use do_all_continuations with 1 as
	'error' parameter.  Pass 0 as 'error' parameter in existing uses
	of discard_all_continuations.
	* infcmd.c (step_1): Do not use exec cleanup.  For async case, discard
	cleanups.
	(step_once): Install continuation only after resuming the target.
	(step_1_continuation): Disable longjmp breakpoint on error.
	(finish_command_continuation): Add the error parameter.  Delete
	the finish breakpoint directly, do not use cleanups.
	(finish_command): Do not use exec_cleanups. Always setup
	continuation.  For sync case, immediately run them.
	(attach_command_continuation): Add the error parameter.
	* infrun.c (fetch_inferior_event): Do not use exec cleanups to
	remove step_resume_breakpoint -- adjust delete it directly.
	* interps.c (interp_set): Adjust call to do_all_continations.
	* mi/mi-interp.c (mi_interpreter_exec_continuation): Do not
	do exec cleanups.
	* mi/mi-main.c (mi_cmd_target_select): Do not do exec
	cleanups.
	(mi_cmd_execute): Do not use exec_cleanup.
	(mi_execute_async_cli_command): Simplify the string concatenation
	logic.  Do no use exec cleanup.
	(mi_exec_async_cli_cmd_continuation): New parameter error.
	Free last_async_command.
	* top.c (command_line_handler_continuation): New parameter error.
	* utils.c (exec_cleanup_chain, make_exec_cleanup)
	(do_exec_cleanups): Remove.
	(add_continuation, do_all_continations)
	(add_intermediate_continuation)
	(do_all_intermediate_continuations): New parameter error.