[libc] Remove unused _Thread_local define from headers. (llvm#156967)

vonosmas · web-flow · commit 369b2a783d90 · 2025-09-04T14:02:43.000-07:00
It was added in dd33f9c to describe thread-local errno, but is no longer used in the codebase (with the exception of a single integration test, but the llvm-libc-provided `#define _Thread_local thread_local` is not needed there anyway, since `_Thread_local` is a keyword from C11 onwards.
diff --git a/libc/include/__llvm-libc-common.h b/libc/include/__llvm-libc-common.h
@@ -37,9 +37,6 @@
 #undef _Alignof
 #define _Alignof alignof
 
-#undef _Thread_local
-#define _Thread_local thread_local
-
 #undef __NOEXCEPT
 #if __cplusplus >= 201103L
 #define __NOEXCEPT noexcept
