Compiled on X8DTU with 2 physical Intel Xeon E5530 CPU (8C16T)

Compile Flags:
CFLAGS='-mtune=generic -Os -pipe -fuse-linker-plugin -flto -fno-exceptions'
CXXFLAGS='-mtune=generic -Os -pipe -fuse-linker-plugin -flto -fno-exceptions -fno-rtti'
LDFLAGS='-Wl,-O1'

# use "-fcommon" to avoid multiple definition
# http://lists.busybox.net/pipermail/buildroot/2020-August/289980.html
# https://www.keil.com/support/man/docs/armclang_ref/armclang_ref_chr1422532346348.htm

CFLAGS="${CFLAGS} -fcommon"
CXXFLAGS="${CXXFLAGS} -fcommon"

export CFLAGS CXXFLAGS LDFLAGS

Dependencies:
mercurial   --> hg clone
autoconf
autogen-dev
automake
compiletc
libX11-dev
libjpeg-turbo-dev
fltk-xft-dev
mbedtls-dev  --> for HTTPS/SSL/TLS
wget

Commands:

# use '--insecure' to bypass '[SSL: CERTIFICATE_VERIFY_FAILED]'
hg clone --insecure http://hg.dillo.org/dillo dillo3-2022-Jan-06

cd dillo3-2022-Jan-06

# replace fltk-config
sudo rm /usr/local/bin/fltk-config
sudo ln -s /usr/local/bin/fltk-config-xft /usr/local/bin/fltk-config

# just in case
sudo rm -f /etc/ld.so.preload

./autogen.sh

mkdir build && cd build

../configure --prefix=/usr/local --enable-ssl --disable-ipv6 --localstatedir=/var

# check flags
find -name Makefile -exec grep '\-g$' {} +
find -name Makefile -exec grep '\-g ' {} +
find -name Makefile -exec grep '\-O[2-9]' {} +

time make -j15
real    0m 29.60s
user    5m 22.44s
sys     0m 14.21s

# verify RPATH, should be [/usr/local/lib/fltk-xft]
readelf -d ./src/dillo | grep RPATH

make DESTDIR=/tmp/dillo-xft install-strip

# before packing
mv /tmp/dillo-xft/usr/local/bin/dillo /tmp/dillo-xft/usr/local/bin/dillo-xft

# add icon and desktop config