https://bugs.gentoo.org/931607
https://github.com/SDL-Hercules-390/hyperion/pull/658

From 655f179dbf34a3b1e9714691462faa9732257937 Mon Sep 17 00:00:00 2001
From: matoro <matoro@users.noreply.github.com>
Date: Thu, 9 May 2024 12:36:01 -0400
Subject: [PATCH] Add missing includes to configure script

This is needed for gcc 14 and clang 16 as they both make implicit
function definitions a hard error.  In a configure script, this means
these tests will switch from passing to failing, which likely means
features will get unintentionally flipped as configure now thinks you
don't have support.

See: https://wiki.gentoo.org/wiki/Modern_C_porting
See: https://bugs.gentoo.org/931607
---
 autoconf/hercules.m4 | 1 +
 configure.ac         | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/autoconf/hercules.m4 b/autoconf/hercules.m4
index cb962f5e0..4d35cb039 100755
--- a/autoconf/hercules.m4
+++ b/autoconf/hercules.m4
@@ -380,6 +380,7 @@ AC_DEFUN([HC_CHECK_NEED_GETOPT_OPTRESET],
             AC_TRY_LINK(
                 [],
                 [
+                    #include <unistd.h>
                     extern int optreset;
                     optreset=1;
                     getopt(0,0,0);
diff --git a/configure.ac b/configure.ac
index f444a9b1e..bfe31357d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1872,6 +1872,8 @@ if test "$GCC" = "yes"; then
                             -g -O2 -fomit-frame-pointer
                     */
 
+                    #include <string.h>
+
                     int foo ()
                     {
                         char a[50000+16];