1.0.28.49: allow stack allocation for arguments of FILL and REPLACE

1.0.28.49: allow stack allocation for arguments of FILL and REPLACE

   FUN-INFO-RESULT-ARG is either NIL, or the index of the argument
   that is EQ to the result of the function. Use LVAR-GOOD-FOR-DX-P
   with the argument lvar that is the result argument.

   Other arguments are for DX as well: if the result can be stack
   allocated then unless the other arguments are otherwise accessible
   they too can be stack allocated -- and if they are otherwise accessible
   then DX analysis should refuse to stack allocate.