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

[Chris Apple via llvm-commits]

cjappl wrote:

Build is failing for same reason as yesterday, still unrelated:

```
_bk;t=1724431385857FAIL: lldb-shell :: Unwind/trap_frame_sym_ctx.test (1944 of 2593)

_bk;t=1724431385857******************** TEST 'lldb-shell :: Unwind/trap_frame_sym_ctx.test' FAILED ********************

_bk;t=1724431385858Exit Code: 1

_bk;t=1724431385858

_bk;t=1724431385858Command Output (stderr):

_bk;t=1724431385858--


```

https://buildkite.com/llvm-project/github-pull-requests/builds/94386#0191800e-c66f-424b-9029-34abc10006d8

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