[llvm] [AArch64] Optimized generated assembly for bool to svbool_t conversions (PR #83001)

[via llvm-commits]

Lukacma wrote:

> Sure, I can see the tests but I meant from a C/C++ point of view.

It was "simple" casting from bool to svbool_t :
```
svbool_t dup_u16(_Bool x) {
    return svdup_n_b16(x);
}
```

https://github.com/llvm/llvm-project/pull/83001