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

[Shilei Tian via llvm-commits]

shiltian wrote:

It seems like some targets add "-unknown" in the compiler driver.


```
+ /local/mnt/workspace/bots/hexagon-build-02/clang-hexagon-elf/stage1/bin/clang --target=hexagon-unknown-elf-unknown -fverbose-asm -g -S /local/mnt/workspace/bots/hexagon-build-02/clang-hexagon-elf/llvm/clang/test/CodeGenCXX/debug-info-member.cpp -o -
clang: error: version 'elf-unknown' in target triple 'hexagon-unknown-unknown-elf-unknown' is invalid

+ /home/buildbot-worker/bbroot/clang-riscv-rva20-2stage/stage2/bin/clang --target=riscv64-linux-gnu-unknown -g -S /home/buildbot-worker/bbroot/clang-riscv-rva20-2stage/llvm/clang/test/CodeGenCXX/debug-info-byval.cpp -o -
clang: error: version '-unknown' in target triple 'riscv64-unknown-linux-gnu-unknown' is invalid
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/buildbot-worker/bbroot/clang-riscv-rva20-2stage/stage2/bin/FileCheck /home/buildbot-worker/bbroot/clang-riscv-rva20-2stage/llvm/clang/test/CodeGenCXX/debug-info-byval.cpp
```

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