libtiff: Merge branch 'fix_605' into 'master'

From 341588333e9a7bd48ac2910f89415ebba47e56c2 Mon Sep 17 00:00:00 2001
From: Even Rouault <[EMAIL REDACTED]>
Date: Thu, 7 Sep 2023 22:40:59 +0200
Subject: [PATCH] autoconf.ac: fix detection of windows.h for mingw (fixes
 #605)

---
 configure.ac | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index b525eff2..e86208d9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -968,14 +968,14 @@ AM_CONDITIONAL(HAVE_CXX, test "$HAVE_CXX" = "yes")
 
 dnl ---------------------------------------------------------------------------
 dnl Check for Win32 IO: make sure we have windows.h but not cygwin
-dnl this must be after the ogl test, since that looks for windows.h and we
-dnl test it
 dnl ---------------------------------------------------------------------------
 
 AC_ARG_ENABLE(win32-io,
 	      AS_HELP_STRING([--disable-win32-io],
 			     [disable Win32 I/O (Windows only, enabled by default except for Cygwin)]),,)
 
+AC_CHECK_HEADER(windows.h)
+
 win32_io_ok=no
 case "${host_os}" in
     cygwin*)