chore(deps): update mimalloc (v2) submodule to v2.5.1

[Brooooooklyn]

Changes

• mimalloc (v2, default feature) — 989c8ebc (v2.5.0) → 1e884db2 (v2.5.1, 2026-09-01). 15 upstream commits, all build/CI only: MI_USE_CXX is now a tri-state cmake option (DEFAULT keeps the old behavior: C++ only for MSVC/Intel/clang-cl), a clang-cl ldar/stlr workaround in include/mimalloc/atomic.h (Work around clang-cl missing ldar, stlr microsoft/mimalloc#1379), C-mode MSVC builds (#1380), pinned actions, dependabot, MI_MALLOC_VERSION 20501. No allocator source files changed.
• build.rs, the v3 submodule (fix(sys): mimalloc3 v3.5.1 + fix for the process-init thread's thread-done hook #97), and the Rust sources are untouched.

Verification

• macOS: cargo test 6/6, cargo test --features secure 6/6, cargo test --features extended 8/8, libmimalloc-sys-test 258/258 (default and secure).
• Linux (Docker arm64, glibc 2.36, node 22, debug + release builds of example/ on the v2 tree): the worker-first repro from fix(sys): mimalloc3 v3.5.1 + fix for the process-init thread's thread-done hook #97 passes (1 / 64 / 64+4 concurrent workers; Rust threads that reuse the dead worker's TCB 64/64 times), as expected for v2, which still associates the process-init thread with the thread-done key. cargo test 6/6, cargo test --features secure 6/6, libmimalloc-sys-test 258/258 (default and secure).

🤖 Generated with Claude Code

https://claude.ai/code/session_01T34fMrYCf2V13Mg8BKmnda

---

Note

Low Risk
Submodule-only dependency bump with upstream reporting no allocator source changes; Rust integration is untouched.

Overview
Bumps the default mimalloc v2 git submodule (libmimalloc-sys/c_src/mimalloc) from v2.5.0 to v2.5.1. This is a pointer-only change in this repo: build.rs, Rust sources, and the v3 submodule are unchanged.

Upstream v2.5.1 is build/CI-focused (tri-state MI_USE_CXX, clang-cl ldar/stlr workaround in atomic.h, C-mode MSVC builds, pinned actions, MI_MALLOC_VERSION 20501). No mimalloc allocator implementation files changed in that release.

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Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-04T15:28:43.627034Z	ed0f9ad	PR opened

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