SDL: x11: fix compilation failure on older XInput2 (06a6a)

SDL Commits
1 
From 06a6adf2b09d24209a12a8726cae5b4f8750da86 Mon Sep 17 00:00:00 2001
From: bubbleguuum <[EMAIL REDACTED]>
Date: Tue, 6 Jan 2026 15:12:03 +0100
Subject: [PATCH] x11: fix compilation failure on older XInput2

Older versions of XInput2 do not declare struct XIGesturePinchEvent
in XInput2.h, causing compilation failure in SDL_x11xinput2.c

Check for XIGesturePinchEvent in the test for enabling
SDL_VIDEO_DRIVER_X11_XINPUT2_SUPPORTS_GESTURE

(cherry picked from commit 7690e00f42fca7444c47bde19be491f617ee8ec7)
---
 cmake/sdlchecks.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmake/sdlchecks.cmake b/cmake/sdlchecks.cmake
index 281c5f63d0697..8df17dd32bed7 100644
--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -457,7 +457,7 @@ macro(CheckX11)
               #include <X11/Xproto.h>
               #include <X11/extensions/XInput2.h>
               int event_type = XI_GesturePinchBegin;
-              XITouchClassInfo *t;
+              XIGesturePinchEvent *t;
               Status XIAllowTouchEvents(Display *a,int b,unsigned int c,Window d,int f) {
                 return (Status)0;
               }