Moved the 'changes' from this patch back to the second so it's all just 
about removing code that we no longer use. I don't really know why Joel 
formatted the patches this way, but I thought I'd keep it as is for now.

cover letter:

This patch removes the old widen plus/minus tree codes which have been
replaced by internal functions.

gcc/ChangeLog:

2023-05-12  Andre Vieira  <andre.simoesdiasvieira@arm.com>
             Joel Hutton  <joel.hutton@arm.com>

	* cfgexpand.cc (expand_debug_expr): Remove old tree codes.
	* doc/generic.texi: Likewise.
	* expr.cc (expand_expr_real_2): Likewise.
	* gimple-pretty-print.cc (dump_binary_rhs): Likewise.
	* gimple-range-op.cc (gimple_range_op_handler::maybe_non_standard):
	Likewise.
	* optabs-tree.cc (optab_for_tree_code): Likewise.
	(supportable_half_widening_operation): Likewise.
	* optabs.cc (commutative_optab_p): Likewise.
         * optabs.def (OPTAB_D): Likewise.
         * tree-cfg.cc (verify_gimple_assign_binary): Likewise.
	* tree-inline.cc (estimate_operator_cost): Likewise.
	(op_symbol_code): Likewise.
	* tree-pretty-print.cc (dump_generic_node): Remove tree code definition.
	* tree-vect-data-refs.cc (vect_get_smallest_scalar_type): Likewise.
	(vect_analyze_data_ref_accesses): Likewise.
	* tree-vect-generic.cc (expand_vector_operations_1): Likewise.
	* tree-vect-stmts.cc (vectorizable_conversion): Likewise.
	(supportable_widening_operation): Likewise.
	* tree.def (WIDEN_PLUS_EXPR, WIDEN_MINUS_EXPR, VEC_WIDEN_PLUS_HI_EXPR,
	VEC_WIDEN_PLUS_LO_EXPR, VEC_WIDEN_MINUS_HI_EXPR,
	VEC_WIDEN_MINUS_LO_EXPR): Likewise.