[llvm] [DebugCounter] Add support for non-continous ranges. (PR #89470)

[Nikita Popov via llvm-commits]

nikic wrote:

After this change, how are you supposed to set a debug counter to zero (as in the old `-count=0`)? I tried `-debug-counter=name=` but that produces an error.

https://github.com/llvm/llvm-project/pull/89470