ax_gromacs.m4: better help for '--with-libgmx'
ax_gromacs.m4: better help for '--with-libgmx'

junghans/csg,junghans/csg,MrTheodor/csg,votca/csg,MrTheodor/csg,MrTheodor/csg,votca/csg,junghans/csg,MrTheodor/csg,votca/csg,junghans/csg,junghans/csg,votca/csg,junghans/csg,MrTheodor/csg