[llvm] [Offload] Fix the wrong signature of `main` function in two tools (PR #99733)

[Shilei Tian via llvm-commits]

shiltian wrote:

> I thought that this was a legal `main` configuration?

Hmm, yeah, you are right. Apparently this is not the only use case in LLVM project. TableGen and FileCheck are also using this. 

https://github.com/llvm/llvm-project/pull/99733