'S' status call- this was the size of the original mtget structure. Don't
bother to map the current mtget structure to an old one- for version 0
RMT it's meaningless because it's all binary data anyway, and it's only the
wierd edge case of Solaris 7 starting to use the 'S' status call that has
tickled this issue- and this MNC fixes that issue.
We need to implement Version 1 RMT anyway.
Approved: jkh@freebsd.org
PR: 14946