[patch/rfc] Simplify target stack

[Andrew Cagney]

> 2003-10-15  Andrew Cagney  <cagney@redhat.com>
> 
> 	* target.c (target_stack): Change to a static target_ops.
> 	(update_current_target): Walk the "struct target_ops" stack.
> 	(pop_target, do_xfer_memory, target_info): Ditto.
> 	(find_target_beneath): Ditto.
> 	(push_target): Rewrite to use the "struct target_ops" stack.
> 	(unpush_target): Ditto.
> 	* target.h (struct target_stack_item): Delete definition.
> 	(target_stack): Delete declaration.
> 	(struct target_ops): Add field "beneath".
> 
I've checked this in.

Andrew