tce-load -i qt-4.x-bin qt-4.x-dev muparser-dev boost-dev

cd LibreCAD-master

Edit
/usr/local/share/qt4/mkspecs/common/gcc-base.conf
/usr/local/share/qt4/mkspecs/common/g++-base.conf

substitute -flto -fuse-linker-plugin -mtune=generic -Os -pipe for pipe
delete -O2

qmake

make
sudo make install