[llvm] [WPD] Change Devirt Cutoff to use DebugCounter (PR #170009)

[Mingming Liu via llvm-commits]

mingmingl-llvm wrote:

fyi I'm planning to land https://github.com/llvm/llvm-project/pull/170011/files after this change to make the multi-line RUN statement easier to modify.

https://github.com/llvm/llvm-project/pull/170009