2006-10-17	Steve Rodrigues <steverod@netapp.com>
	* expression.h (enum exp_opcode): Add OP_LAST_INTERNALVAR opcode.
	* eval.c (evaluate_subexp_standard): Process a OP_LAST_INTERNALVAR
	operand to indirectly access the value history.
	* ada-lang.c (resolve_subexp): Support OP_LAST_INTERNALVAR.
	* expprint.c (print_subexp_standard): Support OP_LAST_INTERNALVAR.
	(op_name_standard): Support OP_LAST_INTERNALVAR. 
	(dump_subexp_body_standard): Support OP_LAST_INTERNALVAR.
	* parse.c (write_dollar_variable): Support '$$' to be treated as
	an OP_LAST_INTERNALVAR.