Add fcntl lock stubs
File lock may be needed for some apps using netcdf+hdf5.
However, we can return 0 with GekkoFS and still it will be valid, as the app is doing the locking also.
``
case F_GETLK:
case F_SETLK:
LOG(DEBUG, "{}() F_*LK on fd {} - cmd {}", __func__, fd, cmd);
return 0;