[llvm] Fix to account for multiple ISA enumeration (PR #118676)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

> Also, this PR doesn't have proper prefix, such as `[Offload][AMDGPU]`.

Forgot to fix that before I hit merge.

> This is not a short term fix. The iteration always starts from specific to generic, so there must be only one match. It is just code error not stopping it on the first match.

That's not what the code is doing, it's copying out the first result to *then* do a comparison. Maybe we could move the check inside of the iterate callback and then break when we first find a match?

> I also don't think it's a good idea to maintain a match table at OpenMP level.

Not the OpenMP level, we need one at the ELF flags level.

https://github.com/llvm/llvm-project/pull/118676