MFC: Lock the vnode interlock while reading v_usecount to update si_usecount in a cdev in devfs_reclaim().
MFC: Lock the vnode interlock while reading v_usecount to update
si_usecount in a cdev in devfs_reclaim().

Approved by:	re (gnn)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase