sdl2-compat: SDL_config_unix.h: Describe our basis for assuming that headers exist

From 4908e8b8ac7ea37d000d59b9e09031ccdb4457e2 Mon Sep 17 00:00:00 2001
From: Simon McVittie <[EMAIL REDACTED]>
Date: Tue, 4 Feb 2025 19:59:01 +0000
Subject: [PATCH] SDL_config_unix.h: Describe our basis for assuming that
 headers exist

Some of these are Standard C, some are POSIX, and a few are non-standard
but widely available.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 include/SDL2/SDL_config_unix.h | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/include/SDL2/SDL_config_unix.h b/include/SDL2/SDL_config_unix.h
index e3ae922..7ac920d 100644
--- a/include/SDL2/SDL_config_unix.h
+++ b/include/SDL2/SDL_config_unix.h
@@ -33,27 +33,31 @@
 
 #define HAVE_GCC_ATOMICS 1
 
-/* Useful headers */
+/* Assume that any reasonable Unix platform has Standard C headers */
 #define STDC_HEADERS 1
-#define HAVE_ALLOCA_H 1
 #define HAVE_CTYPE_H 1
 #define HAVE_FLOAT_H 1
-#define HAVE_ICONV_H 1
 #define HAVE_INTTYPES_H 1
 #define HAVE_LIMITS_H 1
-#define HAVE_MALLOC_H 1
 #define HAVE_MATH_H 1
-#define HAVE_MEMORY_H 1
 #define HAVE_SIGNAL_H 1
 #define HAVE_STDARG_H 1
 #define HAVE_STDINT_H 1
 #define HAVE_STDIO_H 1
 #define HAVE_STDLIB_H 1
-#define HAVE_STRINGS_H 1
 #define HAVE_STRING_H 1
-#define HAVE_SYS_TYPES_H 1
 #define HAVE_WCHAR_H 1
 
+/* Assume that any reasonable Unix platform has POSIX headers */
+#define HAVE_ICONV_H 1
+#define HAVE_STRINGS_H 1
+#define HAVE_SYS_TYPES_H 1
+
+/* Non-standardized, but we assume they exist anyway */
+#define HAVE_ALLOCA_H 1
+#define HAVE_MALLOC_H 1
+#define HAVE_MEMORY_H 1
+
 #define SDL_VIDEO_DRIVER_X11 1
 
 #if defined(__LINUX__)