build: enable multithreading for erofs compression

[robin-reckmann]

Enable multithreading support for erofs compression.

single-thread

real    3m58.763s
user    0m0.091s
sys     0m0.234s

multi-thread

real    1m18.584s
user    0m0.072s
sys     0m0.189s

[github-actions]

vamOS System Profile

Changes vs master

Metric	Change
Used space	3476.7MB → 3476.7MB (0MB)
Sparse image	3430.0MB → 3429.3MB (-.6MB)
Package count	523 → 523

Directory size changes (>1MB)

Directory	Change

---

Metric	Value
Used space	3476.7MB / 5959.5MB
Files	55673
Directories	4435
Symlinks	3459
Packages	523

Top 10 Directories

Directory	Size

Category Breakdown

Category	Size	%
xbps packages	2483.6MB	71.4%
Python venv	655.3MB	18.8%
Firmware	11.5MB	.3%
Other	326.1MB	9.3%

Top 10 Packages by Size

Package	Size
mit-krb5-libs-1.21.3_1	270.4MB
gawk-5.3.2_1	210.3MB
llvm-21_3	148.6MB
libldns-1.9.0_1	124.3MB
pd-mapper-1.0_1	74MB
libclang21-21.1.7_1	70.2MB
glib-2.86.1_2	67.1MB
gcc-14.2.1+20250405_4	65.4MB
libcap-progs-2.77_1	56MB
cmake-4.2.2_1	53.2MB

Top 30 Files by Size

File	Size
/usr/lib/llvm/21/lib/libLLVM.so.21.1	124.3MB
/usr/lib/llvm/21/lib/libMLIR.so.21.1	89.7MB
/usr/lib/llvm/21/bin/mlir-transform-opt	82.9MB
/usr/lib/llvm/21/lib/libclang-cpp.so.21.1	56MB
/usr/lib/llvm/21/bin/mlir-translate	53.2MB
/usr/lib/llvm/21/bin/llvm-exegesis	52MB
/usr/lib/llvm/21/bin/llvm-bolt-binary-analysis	50.6MB
/usr/local/venv/lib/python3.12/site-packages/ffmpeg/install/lib/libavcodec.a	50.5MB
/usr/bin/uv	48.1MB
/usr/lib/gcc/aarch64-linux-gnu/14.2/gnat1	40.1MB
/usr/bin/gdb	38.1MB
/usr/lib/gcc/aarch64-linux-gnu/14.2/cc1plus	37.3MB
/usr/lib/libgallium-25.3.3.so	35.4MB
/usr/lib/libllvm-qcom.so	35.2MB
/usr/lib/gcc/aarch64-linux-gnu/14.2/cc1	35.2MB
/usr/lib/gcc/aarch64-linux-gnu/14.2/lto1	33.9MB
/usr/bin/lto-dump	33.9MB
/usr/lib/libRusticlOpenCL.so.1.0.0	32.5MB
/usr/local/venv/bin/ruff	31.8MB
/usr/share/icu/78.2/icudt78l.dat	31.5MB
/usr/lib/llvm/21/lib/libclang.so.21.1.7	30.2MB
/usr/lib/llvm/21/bin/c-index-test	28.6MB
/usr/local/venv/lib/python3.12/site-packages/gcc_arm_none_eabi/toolchain/libexec/gcc/arm-none-eabi/13.2.1/cc1	28.2MB
/usr/lib/libz3.so	27.9MB
/usr/bin/run	26.6MB
/usr/local/venv/lib/python3.12/site-packages/numpy.libs/libscipy_openblas64_-71e1b124.so	23.6MB
/usr/comma/updater	23.5MB
/usr/comma/setup	23.5MB
/usr/comma/reset	23.5MB
/usr/local/uv/python/cpython-3.12.13-linux-aarch64-gnu/bin/python3.12	22.1MB