sdl2-compat: Add headers available on all platforms

From 1c2269ebf30c193de7df526e54099a66e28013c1 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 31 Jan 2025 09:01:46 -0800
Subject: [PATCH] Add headers available on all platforms

This should help with applications building against sdl2-compat and relying on SDL to include stdio.h for example.

Fixes https://github.com/libsdl-org/SDL_image/issues/511
---
 include/SDL2/SDL_config.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/SDL2/SDL_config.h b/include/SDL2/SDL_config.h
index 057d0c0..3cdcde8 100644
--- a/include/SDL2/SDL_config.h
+++ b/include/SDL2/SDL_config.h
@@ -59,6 +59,15 @@
 
 /* DEFINES ADDED BY SDL2-COMPAT */
 
+#define STDC_HEADERS 1
+#define HAVE_CTYPE_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_MATH_H 1
+#define HAVE_SIGNAL_H 1
+#define HAVE_STDINT_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STRING_H 1
+
 /* Some programs (incorrectly, probably) check defines that aren't available
    with an SDL2 that doesn't have a configure-generated SDL_config.h, so force
    a few that might be important. */