WIP: snapshot mounts, missing refs

Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _dounmount
Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _lookupnameat
Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _mount_snapshot
Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _traverse
Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _vn_matchops
Aug 26 16:51:01 Lundmans-Mac kernel[0]: kxld[net.lundman.zfs]:  _vn_mountedvfs
Fix compile and link of snapdir support, still missing mounts