https://github.com/dajobe/raptor/pull/55

From b7c252e1d5601321a5a6f6627745753b5c704762 Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Fri, 4 Nov 2022 01:53:32 +0000
Subject: [PATCH] configure.ac: fix -Wimplicit-function-declaration in
 HAVE___FUNCTION__ test

This breaks with Clang 16 which makes such errors fatal:
```
error: call to undeclared library function 'printf' with type 'int (const char *, ...)'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
error: call to undeclared library function 'printf' with type 'int (const char *, ...)'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
```

Signed-off-by: Sam James <sam@gentoo.org>
--- a/configure.ac
+++ b/configure.ac
@@ -335,7 +335,8 @@ AC_C_BIGENDIAN
 AC_C_INLINE
 
 AC_MSG_CHECKING(whether __FUNCTION__ is available)
-AC_COMPILE_IFELSE([AC_LANG_SOURCE([int main() { printf(__FUNCTION__); }])],
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([#include <stdio.h>
+int main() { printf(__FUNCTION__); }])],
     [AC_DEFINE([HAVE___FUNCTION__], [1], [Is __FUNCTION__ available])
      AC_MSG_RESULT(yes)],
     [AC_MSG_RESULT(no)])