[llvm] Use DIExpression::foldConstantMath() at the result of an appendOpsToArg() (PR #71721)

[Shubham Sandeep Rastogi via llvm-commits]

rastogishubham wrote:

@SLTozer After taking your feedback into account, I believe I have a solution that is more appropriate. [The compile time](https://llvm-compile-time-tracker.com/compare.php?from=82a8c1cf35e6794d4d1e56797d58abbed0112ad9&to=abbe25add5dc055405f84b59f8baa7d8b2faf795&stat=instructions%3Au) is not significanlty higher, and the [file size](https://llvm-compile-time-tracker.com/compare.php?from=82a8c1cf35e6794d4d1e56797d58abbed0112ad9&to=abbe25add5dc055405f84b59f8baa7d8b2faf795&stat=size-file) reduction is the same.

I would like to note that the size of the file will go down, because currently `DIExpression::foldConstantMath` doesn't fold signed operations, and doesn't fold the logical operations either. Please let me know what you think

https://github.com/llvm/llvm-project/pull/71721