SDL: Fix missing #include in SDL_blendmode.h

From f229e940a41508f0b873243b7b7b02f2f19c6187 Mon Sep 17 00:00:00 2001
From: Susko3 <[EMAIL REDACTED]>
Date: Wed, 15 May 2024 18:57:00 +0200
Subject: [PATCH] Fix missing #include in SDL_blendmode.h

Regressed when SDL_BlendMode was changed from an enum to a typedef Uint32.
---
 include/SDL3/SDL_blendmode.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/SDL3/SDL_blendmode.h b/include/SDL3/SDL_blendmode.h
index ada34362a616b..3c89bcb071351 100644
--- a/include/SDL3/SDL_blendmode.h
+++ b/include/SDL3/SDL_blendmode.h
@@ -28,6 +28,8 @@
 #ifndef SDL_blendmode_h_
 #define SDL_blendmode_h_
 
+#include <SDL3/SDL_stdinc.h>
+
 #include <SDL3/SDL_begin_code.h>
 /* Set up for C function definitions, even when using C++ */
 #ifdef __cplusplus