Based on input from ru & rodrigc document the mount operation in the new
world order:
mount -t linsysfs linsys /compat/linux/sys
instead of mount_linsysfs. Now that 6.X requires mount_linsysfs to
work. This is why there is a mount_linsysfs in 6.X and not in -current.

Prompted by: ru
Reviewed by: ru, rodrigc