[llvm] [ArgPromotion] Handle pointer arguments of recursive calls (PR #78735)

[Vedant Paranjape via llvm-commits]

vedantparanjape-amd wrote:

> > Done, please take a look! adding the testcases in sometime.
> 
> The test is the most important part of the review

I have added the testcase as well, and addressed the comments best I could.

https://github.com/llvm/llvm-project/pull/78735