[clang] [Serialization] [ASTWriter] Try to not record namespace as much as possible (PR #179178)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> This is causing behavior changes for us. Working on getting a reproducer.

Seems related. You can revert this after providing a reproducer.

BTW, who is the person that I need to contact for testing related changes? I pinged @jtstogel but he seems not active. Should I ping you @boomanaiden154 or @alanzhao1  or anyone else to test similar things. Revert after landing is common but we can try to avoid it.

https://github.com/llvm/llvm-project/pull/179178