Resurrect the previous shells/ksh93 as shells/ast-ksh, a ksh93 port
that the maintainer wishes to use to create a shared library for use
with other applications such as CDE. It is based on ksh93v (2014-12-24)
and is incompatible with the direction that att/ast is taking the
official ksh93 implementation.

PR: 237332
Requested by: maintainer (saper@saper.info)