autotools: start new tree so we can re-organise how autoconf, automake and
libtool are handled. We want to have as little of the Starlink build support
files in the various repositories as we can so that merges are easier. The
remaining problem with this idea is that any modifications require that the
distributed files are re-created so we still a lot of configure and
Makefile.in files updated.
autotools: add automake and libtool