abort always dispatches to VM bytecode, to detect same-invocation aborts

* libguile/control.h:
* libguile/control.c (scm_c_make_prompt): Take an extra arg, a cookie.
  Continuations will be rewindable only if the abort has the same cookie
  as the prompt.
  (scm_at_abort): Redefine from scm_abort, and instead of taking rest
  args, take the abort values as a list directly. Also, don't allow
  rewinding, because we won't support rewinding the C stack with
  delimited continuations.

* libguile/eval.c (eval): Adapt to scm_c_make_prompt change.

* libguile/vm-engine.c (vm_engine): Use vp->cookie to get a unique value
  corresponding to this VM invocation.
* libguile/vm-i-system.c (prompt): Pass the cookie to scm_c_make_prompt.
  (abort): Take an additional tail arg.
* libguile/vm.c (vm_abort): Parse out the abort tail arg. This is for
  the @abort case, or the (apply abort ...) case.
  (make_vm): Initialize the cookie to 0.
* libguile/vm.h (struct scm_vm): Add cookie.

* module/ice-9/boot-9.scm (abort): Define here as a trampoline to
  @abort. Needed to make sure that a call to abort dispatches to a VM
  opcode, so the cookie will be the same.

* module/language/tree-il.scm (<tree-il>): Add a "tail" field to
  <abort>, for the (apply abort ...) case, or (@abort tag args). Should
  be #<const ()> in the normal case. Add support throughout.
* module/language/tree-il/analyze.scm (analyze-lexicals): Add abort-tail
  support here too.

* module/language/tree-il/compile-glil.scm (flatten): Compile the tail
  argument appropriately.
* module/language/tree-il/primitives.scm (*primitive-expand-table*): Fix
  @abort and abort cases to pass the tail arg to make-abort.

libguile/vm-engine.c

@@ -47,7 +47,9 @@ VM_NAME (SCM vm, SCM program, SCM *argv, int nargs)
   SCM *objects = NULL;			/* constant objects */
   size_t object_count = 0;              /* length of OBJECTS */
   SCM *stack_limit = vp->stack_limit;	/* stack limit address */
+
   SCM dynstate = SCM_I_CURRENT_THREAD->dynamic_state;
+  scm_t_int64 vm_cookie = vp->cookie++;
 
   /* Internal variables */
   int nvalues = 0;