[clang] [llvm] [LLVM][Triple][NFCI] Add function to test for offloading triples (PR #126956)

[Shilei Tian via cfe-commits]

https://github.com/shiltian approved this pull request.

LGTM but I'd like to get a second stamp on it.

https://github.com/llvm/llvm-project/pull/126956