[llvm] Revert "[Cygwin] Define LLVM_ABI for Cygwin (#143222)" (PR #144210)

[Tomohiro Kashiwada via llvm-commits]

https://github.com/kikairoya created https://github.com/llvm/llvm-project/pull/144210

Flang Merge CI rejects changes to llvm/Support/Compiler.h because precompiled headers aren't rebuilt when their dependencies change.

This reverts commit 60d000496b5485c89c51e64b2b339210d48263be.

>From 16fad5a97d55211ba503f34ccb712c5c67e84e60 Mon Sep 17 00:00:00 2001
From: kikairoya <kikairoya at gmail.com>
Date: Sat, 14 Jun 2025 15:58:01 +0900
Subject: [PATCH] Revert "[Cygwin] Define LLVM_ABI for Cygwin (#143222)"

Flang Merge CI rejects changes to llvm/Support/Compiler.h because precompiled
headers aren't rebuilt when their dependencies change.

This reverts commit 60d000496b5485c89c51e64b2b339210d48263be.
---
 llvm/include/llvm/Support/Compiler.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index 0de789ec68c49..f6bc05011e3c3 100644
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -209,7 +209,7 @@
 #define LLVM_ABI_FRIEND LLVM_ABI
 #define LLVM_ABI_EXPORT __declspec(dllexport)
 #elif defined(__ELF__) || defined(__MINGW32__) || defined(_AIX) ||             \
-    defined(__MVS__) || defined(__CYGWIN__)
+    defined(__MVS__)
 #define LLVM_ABI LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
 #define LLVM_ABI_FRIEND
 #define LLVM_TEMPLATE_ABI LLVM_ATTRIBUTE_VISIBILITY_DEFAULT