SDL: cmake: HAVE_LINUX_VERSION_H is unused

SDL Commits
1 
From 562a8209d8d84e3cb3a4afe0fdbd4f94d0649f91 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Sat, 7 Jan 2023 16:57:28 +0100
Subject: [PATCH] cmake: HAVE_LINUX_VERSION_H is unused

---
 CMakeLists.txt | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7417aa5f89a3..5f16a5848ecd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1585,11 +1585,6 @@ elseif(UNIX AND NOT APPLE AND NOT RISCOS AND NOT HAIKU)
     endif()
   endif()
 
-  check_include_file(linux/version.h HAVE_LINUX_VERSION_H)
-  if(HAVE_LINUX_VERSION_H)
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DHAVE_LINUX_VERSION_H")
-  endif()
-
   if(SDL_MISC)
     file(GLOB MISC_SOURCES ${SDL3_SOURCE_DIR}/src/misc/unix/*.c)
     list(APPEND SOURCE_FILES ${MISC_SOURCES})