dm_target_autoload clobbers linker_file->userrefs with an unsynchronized '=1' store outside kld_lock, racing kldunload's locked read-modify-write — corrupts kld module pin accounting

Summary

The extra-big-hack naked store races locked userrefs RMW in kldload/kldunload - a lost update resurrects a pin or drops a legitimate reference (one kldunload too many admitted, whose failure mode is the DF-5065 freed-text class). Operator-group-reachable autoload side. Delete-the-hack fix (fresh loads already have userrefs=1).