[llvm] [LLVM] Do not require shell for some tests (PR #94595)

[via llvm-commits]

zmodem wrote:

The ones with `ln` are pretty simple :-)

```
'ln': command not found
```

`Other/lit-unicode.txt` is less straight-forward:

```
UnicodeEncodeError: 'charmap' codec can't encode characters in position 6-9: character maps to <undefined>
```

I assumed that's some gnuwin32 thing having poor unicode support.

Both of these can be seen here https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket/8745531620523249025/+/u/package_clang/stdout

https://github.com/llvm/llvm-project/pull/94595