Mimalloc differences from upstream #113141

This issue tracks divergence in our copy of mimalloc from upstream https://github.com/microsoft/mimalloc. The purpose is to help with upstreaming fixes and also so that our modifications are not lost as we pull in new mimalloc versions.

base version: v2.1.2

Simple bug fixes

• gh-90815: Fix mimalloc build on WASI #111524 (fixed upstream)
• gh-111544: Fix mimalloc build on AIX #111593
• gh-111906: Remove unused function warnings during mimalloc build on FREEBSD #111907
• gh-90815: Fix mimalloc atomic.h on Windows arm64 #111527
• gh-112027: Don't print mimalloc warning after mmap() call #113372
• gh-117547: Fix mimalloc compile error on OpenBSD #117548
• gh-117755: Fix mimalloc for huge allocation on s390x #117809
• gh-116984: Make mimalloc header includes relative to the current file #118808
• gh-123022: Fix crash with Py_Initialize in background thread #123052 (May be specific to CPython's usage)
• gh-123826: Fix Unused Static Warnings in Objects/mimalloc/prim/unix/prim.c #123827 (fixed upstream)

Mimalloc changes to support GC

• gh-112532: Use separate mimalloc heaps for GC objects #113263
• gh-112532: Isolate abandoned segments by interpreter #113717
• gh-112532: Tag mimalloc heaps and pages #113742
• gh-112532: Improve mimalloc page visiting #114133
• gh-112529: Use _PyThread_Id() in mimalloc (free-threaded build) #115488

Mimalloc changes for lock-free reads (using QSBR)

• gh-115103: Delay reuse of mimalloc pages that store PyObjects #115435

UWP (Universal Windows Platform) Support

• gh-152433: Windows: allow build mimalloc for UWP #152477