[llvm] [rtsan] Handle attributed IR function declarations (PR #169577)

[Yanzuo Liu via llvm-commits]

zwuis wrote:

> Addresses https://github.com/llvm/llvm-project/issues/169377.

You can use [this format](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue).

https://github.com/llvm/llvm-project/pull/169577