SDL: endian: use TinyCC-compatible output operands for SDL_Swap16.

SDL Commits
1 
From 7bff05402a043512e391d85f026d279d2ad08564 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 23 Oct 2025 11:22:13 -0400
Subject: [PATCH] endian: use TinyCC-compatible output operands for SDL_Swap16.

Closes #14300.
---
 include/SDL3/SDL_endian.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/SDL3/SDL_endian.h b/include/SDL3/SDL_endian.h
index f3ab18ffdc01c..6b1b4cbcf31ed 100644
--- a/include/SDL3/SDL_endian.h
+++ b/include/SDL3/SDL_endian.h
@@ -252,7 +252,7 @@ SDL_FORCE_INLINE Uint16 SDL_Swap16(Uint16 x)
 #elif defined(__x86_64__)
 SDL_FORCE_INLINE Uint16 SDL_Swap16(Uint16 x)
 {
-  __asm__("xchgb %b0,%h0": "=Q"(x):"0"(x));
+  __asm__("xchgb %b0,%h0": "=abcd"(x):"0"(x));
     return x;
 }
 #elif (defined(__powerpc__) || defined(__ppc__))