Compiled on RPI4B-4G with 5.10.77-piCore-v8

Compile Flags:
# error: 'dynamic_cast' not permitted with '-fno-rtti'
CFLAGS='-march=armv8-a+crc -mtune=cortex-a72 -Os -pipe -flto -fuse-linker-plugin -fno-exceptions'
CXXFLAGS='-march=armv8-a+crc -mtune=cortex-a72 -Os -pipe -flto -fuse-linker-plugin -fno-exceptions'
LDFLAGS='-Wl,-O1'
export CFLAGS CXXFLAGS LDFLAGS

Dependencies:
compiletc
llvm-bin

Commands:

wget https://github.com/unicode-org/icu/releases/download/release-70-1/icu4c-70_1-src.tgz

tar -xf icu4c-70_1-src.tgz

cd ./icu/source/

sed -i 's|LDFLAGSICUDT|#LDFLAGSICUDT|' config/mh-linux

# NOTE: I didn't export PKG_CONFIG_PATH
# export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/lib/pkgconfig
./configure --prefix=/usr/local --localstatedir=/var

time make -j4
real    8m 45.88s
user    27m 45.60s
sys     2m 51.72s

DESTDIR=/tmp/packing-icu make install

cd /tmp

# LICENSE
mkdir -p packing-icu-dev/usr/local/share/
mv packing-icu/usr/local/share/icu/ packing-icu-dev/usr/local/share/
mkdir -p packing-icu/usr/local/share/icu/70.1
mv packing-icu-dev/usr/local/share/icu/70.1/LICENSE packing-icu/usr/local/share/icu/70.1

# dev
mkdir -p packing-icu-dev/usr/local/lib
mv packing-icu/usr/local/lib/pkgconfig/ packing-icu-dev/usr/local/lib
mv packing-icu/usr/local/lib/icu/ packing-icu-dev/usr/local/lib
mkdir packing-icu-dev/usr/local/bin
mv packing-icu/usr/local/bin/icu-config packing-icu-dev/usr/local/bin/
mv packing-icu/usr/local/include packing-icu-dev/usr/local/

# doc: manual
mkdir -p packing-icu-doc/usr/local/share/
mv packing-icu/usr/local/share/man/ packing-icu-doc/usr/local/share/

# strip
find packing-icu -exec file {} + | grep ELF | cut -d : -f 1 | xargs strip --strip-unneeded

# bin
mkdir -p packing-icu-bin/usr/local
mv packing-icu/usr/local/*bin packing-icu-bin/usr/local

# chown
sudo chown -R root:root packing-icu*

# squash
for D in packing-icu*; do mksquashfs $D ${D#packing-}.tcz -quiet; done