(svn r4572) Remove vehicle_leave_tile_proc
There's exactly one implemented function (unbarring a level crossing) and one place where it can be triggered (a train leaves a level crossing)
It's a bit overkill, so just handle this one case where it can happen

/* $Id */

#ifndef UNMOVABLE_H
#define UNMOVABLE_H

void UpdateCompanyHQ(Player *p, uint score);

#endif