[clang] [Clang] Include LLVM CodeGen CMake file (PR #109601)

[Tristan Ross via cfe-commits]

https://github.com/RossComputerGuy updated https://github.com/llvm/llvm-project/pull/109601

>From cab2a5cebdc63425ed03a31028e6eb2aee00e5d9 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross at midstall.com>
Date: Sun, 22 Sep 2024 21:02:12 -0700
Subject: [PATCH] [Clang] Include LLVM CodeGen CMake file

---
 clang/lib/CodeGen/CMakeLists.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/clang/lib/CodeGen/CMakeLists.txt b/clang/lib/CodeGen/CMakeLists.txt
index 868ec847b9634b..351a606f65b5be 100644
--- a/clang/lib/CodeGen/CMakeLists.txt
+++ b/clang/lib/CodeGen/CMakeLists.txt
@@ -1,3 +1,7 @@
+if(EXISTS ${LLVM_MAIN_SRC_DIR}/include/llvm/CodeGen AND CLANG_BUILT_STANDALONE)
+  add_subdirectory(${LLVM_MAIN_SRC_DIR}/include/llvm/CodeGen llvm/lib/CodeGen)
+endif()
+
 set(LLVM_LINK_COMPONENTS
   AggressiveInstCombine
   Analysis