Add partitionalloc

[jvoisin]

@1c3t3a expressed interest in adding PartitionAlloc to our allocators collection!

[jvoisin]

https://github.com/daanx/mimalloc-bench/actions/runs/4527308147

 Resolving deltas: 100% (8/8), done.
________ running 'python3 partition_alloc_builder/build/linux/sysroot_scripts/install-sysroot.py --arch=x86' in '/__w/mimalloc-bench/mimalloc-bench/extern/pa'
Installing Debian bullseye i386 root image: /__w/mimalloc-bench/mimalloc-bench/extern/pa/partition_alloc_builder/build/linux/debian_bullseye_i386-sysroot
Downloading https://commondatastorage.googleapis.com/chrome-linux-sysroot/toolchain/de629dcc11a6ab1b11e6d66c4180a959c6290097/debian_bullseye_i386_sysroot.tar.xz
________ running 'python3 partition_alloc_builder/build/linux/sysroot_scripts/install-sysroot.py --arch=x64' in '/__w/mimalloc-bench/mimalloc-bench/extern/pa'
Installing Debian bullseye amd64 root image: /__w/mimalloc-bench/mimalloc-bench/extern/pa/partition_alloc_builder/build/linux/debian_bullseye_amd64-sysroot
Downloading https://commondatastorage.googleapis.com/chrome-linux-sysroot/toolchain/3bdb3503702d35520d101fc5eec9a8ab5353149f/debian_bullseye_amd64_sysroot.tar.xz
________ running 'python3 partition_alloc_builder/tools/clang/scripts/update.py' in '/__w/mimalloc-bench/mimalloc-bench/extern/pa'
Downloading https://commondatastorage.googleapis.com/chromium-browser-clang/Linux_x64/clang-llvmorg-17-init-4759-g547e3456-1.tar.xz .......... Done.
ERROR at //build/config/rust.gni:140:22: Script returned non-zero exit code.
    rustc_revision = exec_script("//tools/rust/update_rust.py",
                     ^----------
Current dir: /__w/mimalloc-bench/mimalloc-bench/extern/pa/partition_alloc_builder/out/Default/
Command: python3 /__w/mimalloc-bench/mimalloc-bench/extern/pa/partition_alloc_builder/tools/rust/update_rust.py --print-package-version
Returned 2.
stderr:

python3: can't open file '/__w/mimalloc-bench/mimalloc-bench/extern/pa/partition_alloc_builder/tools/rust/update_rust.py': [Errno 2] No such file or directory

See //build/config/compiler/BUILD.gn:17:1: whence it was imported.
import("//build/config/rust.gni")
^-------------------------------
See //build/config/BUILDCONFIG.gn:348:3: which caused the file to be included.
  "//build/config/compiler:no_unresolved_symbols",
  ^----------------------------------------------