Change ln '--no-dereference' options from '-h' to '-n'

[okdtsk]

ln command on only Mac OSX has -h option to replace a symlink which may point to a directory.
On other platform, this option is named as -n. (I cannot execute ./gow on Debian jessie and CentOS5, 6, 7)

$ man ln
...
     -h    If the target_file or target_dir is a symbolic link, do not follow it.  This is most useful with the -f option, to replace a symlink which may
           point to a directory.
     -n    Same as -h, for compatibility with other ln implementations.
...

[kawamuray]

Good catch, thanks. LGTM 👍