SDL: Add a test to verify structure alignment

SDL Commits
1 
From 04a732881a38c2e67c2662ab136ef143e4cba96d Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 5 Sep 2024 14:22:39 -0700
Subject: [PATCH] Add a test to verify structure alignment

---
 include/SDL3/SDL_stdinc.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/SDL3/SDL_stdinc.h b/include/SDL3/SDL_stdinc.h
index 6fb09b1a7f0f5..646bbd788420b 100644
--- a/include/SDL3/SDL_stdinc.h
+++ b/include/SDL3/SDL_stdinc.h
@@ -494,6 +494,12 @@ SDL_COMPILE_TIME_ASSERT(uint32, sizeof(Uint32) == 4);
 SDL_COMPILE_TIME_ASSERT(sint32, sizeof(Sint32) == 4);
 SDL_COMPILE_TIME_ASSERT(uint64, sizeof(Uint64) == 8);
 SDL_COMPILE_TIME_ASSERT(sint64, sizeof(Sint64) == 8);
+typedef struct SDL_alignment_test
+{
+    Uint8 a;
+    void *b;
+} SDL_alignment_test;
+SDL_COMPILE_TIME_ASSERT(struct_alignment, sizeof(SDL_alignment_test) == (2 * sizeof(void *)));
 #endif /* DOXYGEN_SHOULD_IGNORE_THIS */
 /** \endcond */