[clang] [clang] Stub out gcc_struct attribute (PR #71148)

[Andrew Kaster via cfe-commits]

ADKaster wrote:

> SerenityOS is an OS, independent from Windows. What does porting it to Windows mean? Build some SerenityOS components on Windows targeting the PE object file format?

In this case, Dan is referring to future plans to port the Ladybird browser to x86_64-windows-msvc. The browser and its ports use the system libraries from SerenityOS in the implementation.

https://github.com/llvm/llvm-project/pull/71148