[clang] [llvm] [OffloadBundler] Rework the ctor of `OffloadTargetInfo` to support AMDGPU's generic target (PR #122629)

[Lucas Duarte Prates via llvm-commits]

pratlucas wrote:

I see this change re-landed yesterday but we continue to see failures related to the extra `-unknown` component in our downstream testing of [arm/arm-toolchain](https://github.com/arm/arm-toolchain), which are similar to what was described in the comment above:
```
arm-software/build-atfe-package/clang/test/Driver/debug-options-as.c:88:12: error: DWARF3: expected string not found in input
// DWARF3: "-cc1as"
           ^
<stdin>:1:1: note: scanning from here
clang: error: version '-unknown' in target triple 'aarch64-unknown-linux-gnu-unknown' is invalid
^
```

https://github.com/llvm/llvm-project/pull/122629