Manually backport macOS 15.4 fix for strchrnul

See https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=6da2ba1d8a031984eb016fed6741bb2ac945f19d

Author: lfittl

Diff for: src/postgres/include/pg_config.h

@@ -116,6 +116,10 @@
    don't. */
 #define HAVE_DECL_PWRITEV 1
 
+/* Define to 1 if you have the declaration of `strchrnul', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRCHRNUL
+
 /* Define to 1 if you have the declaration of `strlcat', and to 0 if you
    don't. */
 #define HAVE_DECL_STRLCAT 1
@@ -397,9 +401,6 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #define HAVE_STDLIB_H 1
 
-/* Define to 1 if you have the `strchrnul' function. */
-/* #undef HAVE_STRCHRNUL */
-
 /* Define to 1 if you have the `strerror_r' function. */
 #define HAVE_STRERROR_R 1
 
@@ -851,7 +852,9 @@
 /* Ensure we do not fail on systems that have strchrnul support (FreeBSD, NetBSD and newer glibc) */
 #include <stdlib.h>
 #if defined(__FreeBSD__) || defined(__NetBSD__) || (defined(__GLIBC__) && ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 38) || __GLIBC__ > 2))
-#define HAVE_STRCHRNUL
+#define HAVE_DECL_STRCHRNUL 1
+#else
+#define HAVE_DECL_STRCHRNUL 0
 #endif
 
 /* 32-bit */

Diff for: src/postgres/src_port_snprintf.c

@@ -368,7 +368,9 @@ static void trailing_pad(int padlen, PrintfTarget *target);
  * Note: glibc declares this as returning "char *", but that would require
  * casting away const internally, so we don't follow that detail.
  */
-#ifndef HAVE_STRCHRNUL
+#if !HAVE_DECL_STRCHRNUL
+
+#define strchrnul pg_strchrnul
 
 static inline const char *
 strchrnul(const char *s, int c)
@@ -378,19 +380,7 @@ strchrnul(const char *s, int c)
 	return s;
 }
 
-#else
-
-/*
- * glibc's <string.h> declares strchrnul only if _GNU_SOURCE is defined.
- * While we typically use that on glibc platforms, configure will set
- * HAVE_STRCHRNUL whether it's used or not.  Fill in the missing declaration
- * so that this file will compile cleanly with or without _GNU_SOURCE.
- */
-#ifndef _GNU_SOURCE
-extern char *strchrnul(const char *s, int c);
-#endif
-
-#endif							/* HAVE_STRCHRNUL */
+#endif							/* !HAVE_DECL_STRCHRNUL */
 
 
 /*