[llvm] Revert "Remove dependence on <ciso646>" (PR #126399)

[Jonas Devlieghere via llvm-commits]

https://github.com/JDevlieghere created https://github.com/llvm/llvm-project/pull/126399

Reverts llvm/llvm-project#73273

>From 72b67d9e808f56f835329fda8660f263c28c5b0c Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas at devlieghere.com>
Date: Sat, 8 Feb 2025 20:22:04 -0800
Subject: [PATCH] Revert "Remove dependence on <ciso646> (#73273)"

This reverts commit c89735d289f341985ca2ea74486b96bc611b3c64.
---
 llvm/include/llvm/Support/Threading.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/llvm/include/llvm/Support/Threading.h b/llvm/include/llvm/Support/Threading.h
index 9972f4ad31dadb5..01e26ad9b858ea3 100644
--- a/llvm/include/llvm/Support/Threading.h
+++ b/llvm/include/llvm/Support/Threading.h
@@ -19,7 +19,6 @@
 #include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
 #include "llvm/Support/Compiler.h"
 #include <optional>
-#include <version>
 
 #if defined(_MSC_VER)
 // MSVC's call_once implementation worked since VS 2015, which is the minimum