Revert "[llvm] annotate ABIBreakingChecks symbols for DLL export (llvm#145575)"

This reverts commit 2447540.

Author: andrurogerz

llvm/include/llvm/Config/abi-breaking.h.cmake

@@ -12,9 +12,6 @@
 #ifndef LLVM_ABI_BREAKING_CHECKS_H
 #define LLVM_ABI_BREAKING_CHECKS_H
 
-// Compiler.h is required for LLVM_ABI definition.
-#include "llvm/Support/Compiler.h"
-
 /* Define to enable checks that alter the LLVM C++ ABI */
 #cmakedefine01 LLVM_ENABLE_ABI_BREAKING_CHECKS
 
@@ -46,12 +43,12 @@
 #endif
 namespace llvm {
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
-LLVM_ABI extern int EnableABIBreakingChecks;
+extern int EnableABIBreakingChecks;
 LLVM_HIDDEN_VISIBILITY
 __attribute__((weak)) int *VerifyEnableABIBreakingChecks =
     &EnableABIBreakingChecks;
 #else
-LLVM_ABI extern int DisableABIBreakingChecks;
+extern int DisableABIBreakingChecks;
 LLVM_HIDDEN_VISIBILITY
 __attribute__((weak)) int *VerifyDisableABIBreakingChecks =
     &DisableABIBreakingChecks;