be: Remove arch_set_irn_flags().

The only user should be an arch_add_irn_flags() instead.
It was harmless though, because no other flags were set.

ir/be/bearch.c

@@ -96,12 +96,6 @@ void arch_set_irn_register(ir_node *node, const arch_register_t *reg)
 	out->reg = reg;
 }
 
-void arch_set_irn_flags(ir_node *node, arch_irn_flags_t flags)
-{
-	backend_info_t *const info = be_get_info(node);
-	info->flags = flags;
-}
-
 void arch_add_irn_flags(ir_node *node, arch_irn_flags_t flags)
 {
 	backend_info_t *const info = be_get_info(node);

ir/be/bearch.h

@@ -157,8 +157,6 @@ static inline arch_irn_flags_t arch_get_irn_flags(const ir_node *node)
 	return info->flags;
 }
 
-void arch_set_irn_flags(ir_node *node, arch_irn_flags_t flags);
-
 void arch_add_irn_flags(ir_node *node, arch_irn_flags_t flags);
 
 /**

ir/be/bespillutil.c

@@ -1009,7 +1009,7 @@ static void gen_assure_different_pattern(ir_node *irn, ir_node *other_different,
 	ir_node *cpy = find_copy(skip_Proj(irn), other_different);
 	if (cpy == NULL) {
 		cpy = be_new_Copy(block, other_different);
-		arch_set_irn_flags(cpy, arch_irn_flag_dont_spill);
+		arch_add_irn_flags(cpy, arch_irn_flag_dont_spill);
 		DB((dbg_constr, LEVEL_1, "created non-spillable %+F for value %+F\n", cpy, other_different));
 	} else {
 		DB((dbg_constr, LEVEL_1, "using already existing %+F for value %+F\n", cpy, other_different));