[llvm] [mlir] [OMPIRBuilder] Don't use invalid debug loc in task proxy function. (PR #148284)

[Abid Qadeer via llvm-commits]

abidh wrote:

> Thank you for this PR, @abidh. While this LGTM, i have a question - this seems to be a pattern that is repeating itself. Wouldn't we be better off with a `static` utility function in `OMPIRBuilder.cpp` for creating entry basic blocks in newly created functions which would also set up the debug location correctly?

Thanks @bhandarkar-pranav for the suggestion. I will merge this and open a cleanup PR to add the utility function.

https://github.com/llvm/llvm-project/pull/148284