[llvm] Migrate llvm-profdata to Opt flag parsing (PR #177868)

[David Zbarsky via llvm-commits]

dzbarsky wrote:

> @dzbarsky -- thank you for the PR. I am interested in reviewing this patch but will be a few days before I can get to this as I am returning from a break. In the meanwhile can you take a look at why the builders are failing? There is no regression tests currently for llvm-profdata --help and for other subcommand help text outputs. Can you also consider adding tests for the help text outputs and/or comment on whether you are seeing the behavior of the tool including help text to be correct after these changes? Thank you.

No worries, I'll be traveling later this week/weekend to give a talk about LLVM at Fosdem, so I'll also be delayed :)

It looks like CI discovered that there are some cl::Opt definitions in libs that did not get ported; for now I kept a limited form of CL parsing for those, we will need to fix all upstream tools that use them (probably do their own parsing and thread through options), but it feels like too big a change for a single PR. Let mek now if you have any better ideas!

Added some tests for the help outputs.

https://github.com/llvm/llvm-project/pull/177868