Fix cmake error when no icon is set and support spaces in icon path
Fix cmake error when no icon is set and support spaces in icon path

hpicgs/cmake-init,hpicgs/cmake-init,semperos/cmake-init,j-o/cmake-init,hpicgs/cmake-init,j-o/cmake-init,hpicgs/cmake-init,j-o/cmake-init,sebastiankaybelle/cmake-init,dkushner/quartermaster,sebastiankaybelle/cmake-init,semperos/cmake-init,dkushner/quartermaster,cginternals/cmake-init,cginternals/cmake-init,j-o/cmake-init