in Dockerfile use default compiler
in Dockerfile use default compiler

removes code that sets env for gcc 4.9

mitdrc/director,mitdrc/director,patmarion/director,openhumanoids/director,patmarion/director,patmarion/director,patmarion/director,openhumanoids/director,patmarion/director,openhumanoids/director,mitdrc/director,mitdrc/director,manuelli/director,mitdrc/director,manuelli/director,manuelli/director,openhumanoids/director,manuelli/director,openhumanoids/director,manuelli/director