Fix bug (compilation error on some Linux systems, ambiguous abs() function)
Fix bug (compilation error on some Linux systems, ambiguous abs() function)

rserban/chrono,rserban/chrono,dariomangoni/chrono,armanpazouki/chrono,dariomangoni/chrono,Milad-Rakhsha/chrono,rserban/chrono,armanpazouki/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,rserban/chrono,Milad-Rakhsha/chrono,armanpazouki/chrono,dariomangoni/chrono,projectchrono/chrono,projectchrono/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,rserban/chrono,projectchrono/chrono,rserban/chrono,projectchrono/chrono,armanpazouki/chrono,dariomangoni/chrono,armanpazouki/chrono,Milad-Rakhsha/chrono,rserban/chrono,armanpazouki/chrono,dariomangoni/chrono,projectchrono/chrono,dariomangoni/chrono