SDL: sdlchecks.cmake: Clarified the reason why shared X11 mode doesn't work

From f9baa302707c3b79a841af34416eb95cd09043cc Mon Sep 17 00:00:00 2001
From: Wohlstand <[EMAIL REDACTED]>
Date: Wed, 8 Nov 2023 13:31:12 +0300
Subject: [PATCH] sdlchecks.cmake: Clarified the reason why shared X11 mode
 doesn't work

#6778
---
 cmake/sdlchecks.cmake | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmake/sdlchecks.cmake b/cmake/sdlchecks.cmake
index fc5b096b2df8..815665364785 100644
--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -471,7 +471,9 @@ macro(CheckX11)
       list(APPEND SOURCE_FILES ${X11_SOURCES})
       set(SDL_VIDEO_DRIVER_X11 1)
 
-      # !!! FIXME: why is this disabled for Apple?
+      # Note: Disabled on Apple because the dynamic mode backend for X11 doesn't
+      # work properly on Apple during several issues like inconsistent paths
+      # among platforms. See #6778 (https://github.com/libsdl-org/SDL/issues/6778)
       if(APPLE)
         set(SDL_X11_SHARED OFF)
       endif()