[flang-commits] [flang] [flang][NFC] Fix header guards (PR #85801)

[Tom Eccles via flang-commits]

https://github.com/tblah commented:

Thanks for spotting this and cleaning up.

Personally, I think LLVM_FLANG is a better prefix because it is more specific and looks a bit more like the path to the file. But I don't feel strongly about it.

https://github.com/llvm/llvm-project/pull/85801