[llvm] [Offload] add 'olIterateSymbols' runtime function (PR #213036)

[Alex Duran via llvm-commits]

adurang wrote:

> I did the override, let me know if it works.

Everything passes now. Thanks for taking care of it (i thought a follow-up was fine too).

https://github.com/llvm/llvm-project/pull/213036