[clang] Reland [C++20] [Modules] [Itanium ABI] Generate the vtable in the mod… (PR #102287)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

Although there is an issue report in https://github.com/llvm/llvm-project/issues/98021. But it looks like an existing issue and the previous "fix" is just a "coincidence". So I don't think this is a regression and I like to backport this.

https://github.com/llvm/llvm-project/pull/102287