Fix compilation error.
Fix compilation error.

chrisdembia/simbody,scamille/simbody,simbody/simbody,chrisdembia/simbody,robojukie/simbody,chrisdembia/simbody,simbody/simbody,robojukie/simbody,elen4/simbody,scamille/simbody,Gjacquenot/simbody,elen4/simbody,elkingtonmcb/simbody,elkingtonmcb/simbody,robojukie/simbody,Gjacquenot/simbody,scamille/simbody,elkingtonmcb/simbody,Gjacquenot/simbody