[llvm] [RemoveDIs] Enable conversion from dbg.declare to DPValue (PR #74090)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse approved this pull request.

Overall idea LGTM. In terms of landing things, we've made a mess by having this partial overlapping coverage sadly, so there'll need to be some kind of gap for some period.

An additional constraint however is that there /might/ now be people testing this code, seeing how we've announced testing, and if we land the dbg-declare-conversion code up front, there might be some spurious differences / crashes / whatever in the meantime. I'd prefer option 2 to avoid punishing anyone who's kind enough to test for us.

(Or add another command line flag that lasts two days and turns on dbg-declare conversion? All bad options sorry).

https://github.com/llvm/llvm-project/pull/74090