5045 use atomic_{inc,dec}_* instead of atomic_add_*

*** 177,187 ****
           */
          vfsp->vfs_bsize = DEV_BSIZE;
          vfsp->vfs_fstype = objfs_fstype;
          do {
                  dev = makedevice(objfs_major,
!                     atomic_add_32_nv(&objfs_minor, 1) & L_MAXMIN32);
          } while (vfs_devismounted(dev));
          vfs_make_fsid(&vfsp->vfs_fsid, dev, objfs_fstype);
          vfsp->vfs_data = data;
          vfsp->vfs_dev = dev;
  
--- 177,187 ----
           */
          vfsp->vfs_bsize = DEV_BSIZE;
          vfsp->vfs_fstype = objfs_fstype;
          do {
                  dev = makedevice(objfs_major,
!                     atomic_inc_32_nv(&objfs_minor) & L_MAXMIN32);
          } while (vfs_devismounted(dev));
          vfs_make_fsid(&vfsp->vfs_fsid, dev, objfs_fstype);
          vfsp->vfs_data = data;
          vfsp->vfs_dev = dev;