Skip definition of bool on -std=c23 or newer
https://bugs.gentoo.org/970613
https://src.fedoraproject.org/rpms/ldns/blob/ee1ebc36cd4e1fdc81b9c43f1107c02e0cceb74e/f/ldns-1.9-std23-bool.patch
From: Petr Menšík <pemensik@redhat.com>

--- a/ldns/common.h.in
+++ b/ldns/common.h.in
@@ -40,6 +40,10 @@
  */
 /*@ignore@*/
 /* splint barfs on this construct */
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
+/* c23 defines bool already and deprecates stdbool.h */
+#define __bool_true_false_are_defined
+#endif
 #ifndef __bool_true_false_are_defined
 # ifdef HAVE_STDBOOL_H
 #  include <stdbool.h>