[llvm] [LLVM][rtsan] Add LLVM nosanitize_realtime attribute (PR #105447)

[via llvm-commits]

pcc wrote:

> Re 3: we can always defer adding the attribute until/unless the planned functionality is actually implemented.

Another point regarding this: when adding new functionality to sanitizers we often need to be able to opt out the new functionality in existing code in order to avoid breaking existing usage of the sanitizer. So in the end you might end up needing nonblocking function checks to be controlled separately from loop checks (or any other checks that you may implement in the future). That would likely imply a separate LLVM attribute specifically for loop checks, rendering the LLVM attributes for nonblocking function checks unnecessary.

https://github.com/llvm/llvm-project/pull/105447