[clang] [WebAssembly] Support 0-argument export_name to export with linkage name (PR #221363)

[Alex Crichton via cfe-commits]

alexcrichton wrote:

Personally I don't think I'm equipped to have much of an opinion here insofar as the question @sbc100 you're posing seems to be about C/C++ attribute idioms which I don't have a ton of experience with. It doesn't look like this would affect other frontends emitting LLVM IR directly, so I also don't see anything worrisome here myself too.

https://github.com/llvm/llvm-project/pull/221363