Install the documentation, including info and man pages but not the mdb
docs, into the paths selected by ./configure. This also makes Mercury more
up-to-date with respect to Linux Distros' file locations, using share/doc/
rather than doc/
Doing the same for other files, such as binaries, libraries and the mdb
documentation, requires more working with autoconf than I'm happy to do
right now.
scripts/Mmake.vars.in:
As above.