tce-load -i compiletc pangomm-dev atkmm-dev gtk3-dev

cd gtkmm-3.22.3

edit /usr/local/include/glibmm-2.4/glibmm/threads.h
GPrivate* gobj() { return gobject_; } -> GPrivate* gobj() { return &gobject_; }

CC="gcc -flto -fuse-linker-plugin -march=i486 -mtune=i686 -Os -pipe" CXX="g++ -flto -fuse-linker-plugin -march=i486 -mtune=i686 -Os -pipe" ./configure --prefix=/usr/local --disable-static --localstatedir=/var

find . -name Makefile -type f -exec sed -i 's/-g -O2//g' {} \;

make [7m 18.73s]
sudo make install