Remove tree_code from range-operator.

Remove tree_code from range-operator.

Range_operator had a tree code added last release to facilitate
bitmask operations.  This removes the tree_code and replaces it with a
virtual routine to peform the masking.  Remove any duplicate instances
which are no longer needed.

	* range-op.cc (range_operator::fold_range): Call virtual routine.
	(range_operator::update_bitmask): New.
	(operator_equal::update_bitmask): New.
	(operator_not_equal::update_bitmask): New.
	(operator_lt::update_bitmask): New.
	(operator_le::update_bitmask): New.
	(operator_gt::update_bitmask): New.
	(operator_ge::update_bitmask): New.
	(operator_ge::update_bitmask): New.
	(operator_plus::update_bitmask): New.
	(operator_minus::update_bitmask): New.
	(operator_pointer_diff::update_bitmask): New.
	(operator_min::update_bitmask): New.
	(operator_max::update_bitmask): New.
	(operator_mult::update_bitmask): New.
	(operator_div:operator_div):New.
	(operator_div::update_bitmask): New.
	(operator_div::m_code): New member.
	(operator_exact_divide::operator_exact_divide): New constructor.
	(operator_lshift::update_bitmask): New.
	(operator_rshift::update_bitmask): New.
	(operator_bitwise_and::update_bitmask): New.
	(operator_bitwise_or::update_bitmask): New.
	(operator_bitwise_xor::update_bitmask): New.
	(operator_trunc_mod::update_bitmask): New.
	(op_ident, op_unknown, op_ptr_min_max): New.
	(op_nop, op_convert): Delete.
	(op_ssa, op_paren, op_obj_type): Delete.
	(op_realpart, op_imagpart): Delete.
	(op_ptr_min, op_ptr_max): Delete.
	(pointer_plus_operator:update_bitmask): New.
	(range_op_table::set): Do not use m_code.
	(integral_table::integral_table): Adjust to single instances.
	* range-op.h (range_operator::range_operator): Delete.
	(range_operator::m_code): Delete.
	(range_operator::update_bitmask): New.