[compiler-rt] compiler-rt: Use LLVM_THIRD_PARTY_DIR for siphash include (PR #166097)

[via llvm-commits]

https://github.com/bkuhls created https://github.com/llvm/llvm-project/pull/166097

Introduced by https://github.com/llvm/llvm-project/commit/7f3afab9181d83f92771293ad3b6c00ac62800fd but currently unused in compiler-rt leading to build errors with COMPILER_RT_STANDALONE_BUILD=ON

>From 8fb17d03f8f7cec84dc8d6baebd479c4c34ba74b Mon Sep 17 00:00:00 2001
From: Bernd Kuhls <bernd at kuhls.net>
Date: Sun, 2 Nov 2025 21:18:24 +0100
Subject: [PATCH] compiler-rt: Use LLVM_THIRD_PARTY_DIR for siphash include

Introduced by https://github.com/llvm/llvm-project/commit/7f3afab9181d83f92771293ad3b6c00ac62800fd
but currently unused in compiler-rt leading to build errors with
COMPILER_RT_STANDALONE_BUILD=ON
---
 compiler-rt/lib/builtins/CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 6c226aa7d2d48..7eb5ef487d318 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -64,7 +64,7 @@ include(CMakePushCheckState)
 option(COMPILER_RT_BUILTINS_HIDE_SYMBOLS
   "Do not export any symbols from the static library." ON)
 
-include_directories(../../../third-party/siphash/include)
+include_directories(${LLVM_THIRD_PARTY_DIR}/siphash/include)
 
 # TODO: Need to add a mechanism for logging errors when builtin source files are
 # added to a sub-directory and not this CMakeLists file.