Команда make вызывает такую ошибку
libtool: link: g++ -g -O2 -fopenmp -o .libs/netgen demoview.o ngappinit.o onetcl.o parallelfunc.o ngpkg.o -Wl,--export-dynamic ../libsrc/visualization/.libs/libvisual.a ../libsrc/csg/.libs/libcsgvis.so ../libsrc/csg/.libs/libcsg.so ../libsrc/interface/.libs/libinterface.so ../libsrc/meshing/.libs/libmesh.so -L/usr/lib/Togl1.7 -lTogl -lGLU -L/usr/lib/x86_64-linux-gnu -ltk8.6 -ltcl8.6 -lGL -lXmu -lX11 -fopenmp -Wl,-rpath -Wl,/opt/netgen/lib
/usr/bin/ld: cannot find -lXmu: No such file or directory
collect2: error: ld returned 1 exit status