tce-load -i compiletc cmake gobject-introspection-dev vala-dev icu61-dev

https://github.com/libical/libical/releases/download/v3.0.8/libical-3.0.8.tar.gz

cd libical-3.0.8

mkdir build
cd build

cmake -LAH -DCMAKE_C_FLAGS_RELEASE="-flto -fuse-linker-plugin -mtune=generic -Os -pipe" -DCMAKE_CXX_FLAGS_RELEASE="-flto -fuse-linker-plugin -mtune=generic -Os -pipe" -DCMAKE_INSTALL_PREFIX=/usr/local -DCMAKE_BUILD_TYPE=Release -DCMAKE_VERBOSE_MAKEFILE=TRUE -DSHARED_ONLY=yes -DICAL_BUILD_DOCS=false -DGOBJECT_INTROSPECTION=true -DICAL_GLIB_VAPI=true ../

make [0m 31.83s]
sudo make install