[clang] [Safe Buffers] Serialize unsafe_buffer_usage pragmas (PR #92031)

[Artem Dergachev via cfe-commits]

haoNoQ wrote:

Ok I think I'm completely happy with the patch now. It makes perfect sense to me and appears to be doing the right thing. Thank you @ziqingluo-90 for figuring this out! Let's add that comment and land.

https://github.com/llvm/llvm-project/pull/92031