[llvm] [AIX] Add -pthread to build on AIX (PR #129108)

[Mark Danial via llvm-commits]

https://github.com/madanial0 created https://github.com/llvm/llvm-project/pull/129108

When building in tree clang without having `-pthread`  we get a bunch of `Assertion failed: FD != kInvalidFile && "Invalid or inactive file descriptor"` when testing check-clang. 

>From 70b4bef9c38fa897fafd951d9eaa617df65f02b5 Mon Sep 17 00:00:00 2001
From: Mark Danial <mark.danial at ibm.com>
Date: Thu, 27 Feb 2025 14:01:44 -0500
Subject: [PATCH] Add -pthread to build on AIX

---
 llvm/CMakeLists.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index c9ff3696e22d6..e159a9976651d 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -1182,6 +1182,7 @@ endif()
 if (UNIX AND ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
           add_compile_definitions(_XOPEN_SOURCE=700)
           add_compile_definitions(_LARGE_FILE_API)
+          add_compile_options(-pthread)
 
   # Modules should be built with -shared -Wl,-G, so we can use runtime linking
   # with plugins.