[llvm] [libcxxabi] [ItaniumDemangle] reapply 0e754e114a6 (PR #79488)

[Nico Weber via llvm-commits]

nico wrote:

First windows bot failed with

```
mt.exe : general error c101008d: Failed to write the updated manifest to the resource of file "tools\mlir\unittests\Debug\MLIRDebugTests.exe". Operation did not complete successfully because the file contains a virus or potentially unwanted software.
```

Second with

```
# \| OSError: [WinError 225] Operation did not complete successfully because the file contains a virus or potentially unwanted software
```
I'm going to claim that's unrelated and the interesting part (the build) passed with this.

https://github.com/llvm/llvm-project/pull/79488