Update clang/lib/Basic/Targets/X86.h

Co-authored-by: jeremyd2019 <[email protected]>

Author: kikairoya

clang/lib/Basic/Targets/X86.h

@@ -1024,11 +1024,6 @@ class LLVM_LIBRARY_VISIBILITY CygwinX86_64TargetInfo : public X86_64TargetInfo {
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }
-
-  TargetInfo::CallingConvKind
-  getCallingConvKind(bool ClangABICompat4) const override {
-    return CCK_MicrosoftWin64;
-  }
 };
 
 class LLVM_LIBRARY_VISIBILITY DarwinX86_64TargetInfo