s3: libsmb: Fix reversing of oldname/newname paths when creating a reparse point...

s3: libsmb: Fix reversing of oldname/newname paths when creating a reparse point symlink on Windows from smbclient.

This happened as smbd doesn't support reparse points so we couldn't test.
This was the reverse of the (tested) symlink parameters in the unix extensions
symlink command.

Rename parameters to link_target instead of oldname so this is clearer.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13172

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>