Add declaration for num_shafts (lost during the previous merge operation).
Add declaration for num_shafts (lost during the previous merge operation).

PedroTrujilloV/chrono,hsu/chrono,Bryan-Peterson/chrono,Milad-Rakhsha/chrono,rserban/chrono,andrewseidl/chrono,PedroTrujilloV/chrono,PedroTrujilloV/chrono,projectchrono/chrono,armanpazouki/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,dariomangoni/chrono,tjolsen/chrono,Milad-Rakhsha/chrono,dariomangoni/chrono,armanpazouki/chrono,hsu/chrono,jcmadsen/chrono,armanpazouki/chrono,amelmquist/chrono,rserban/chrono,jcmadsen/chrono,rserban/chrono,PedroTrujilloV/chrono,andrewseidl/chrono,dariomangoni/chrono,dariomangoni/chrono,jcmadsen/chrono,rserban/chrono,armanpazouki/chrono,tjolsen/chrono,hsu/chrono,armanpazouki/chrono,Bryan-Peterson/chrono,amelmquist/chrono,projectchrono/chrono,tjolsen/chrono,andrewseidl/chrono,jcmadsen/chrono,amelmquist/chrono,amelmquist/chrono,PedroTrujilloV/chrono,rserban/chrono,jcmadsen/chrono,rserban/chrono,tjolsen/chrono,projectchrono/chrono,projectchrono/chrono,jcmadsen/chrono,Bryan-Peterson/chrono,hsu/chrono,dariomangoni/chrono,tjolsen/chrono,Milad-Rakhsha/chrono,hsu/chrono,jcmadsen/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,armanpazouki/chrono,rserban/chrono,andrewseidl/chrono,andrewseidl/chrono,Bryan-Peterson/chrono,projectchrono/chrono,projectchrono/chrono,dariomangoni/chrono,Bryan-Peterson/chrono,Milad-Rakhsha/chrono