perf: add a second elim dead vars pass

[hargoniX]

No description provided.

[hargoniX]

!bench

[leanprover-radar]

Benchmark results for ee8152b against 64c0555 are in! @hargoniX

• ✅ build//instructions: -683.7M (-0.01%)

Small changes (3✅)

• ✅ build/module/Init.Simproc//instructions: -45.5M (-0.76%)
• ✅ build/module/Lake.Config.Module//instructions: -11.1M (-0.46%)
• ✅ build/module/Std.Do.SPred.Notation//instructions: -234.8M (-1.12%) (reduced significance based on absolute threshold)

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 64c0555e0b85f19cc228671d066dc177b3749d88 --onto 75d7f7eb227bc54dc6ea3d8ead090ee4180debaf. You can force Mathlib CI using the force-mathlib-ci label. (2026-02-06 23:21:04)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 64c0555e0b85f19cc228671d066dc177b3749d88 --onto 75d7f7eb227bc54dc6ea3d8ead090ee4180debaf. You can force reference manual CI using the force-manual-ci label. (2026-02-06 23:21:05)