back --infodir, which several automatic build environments expect to exist.
Add --without-docdir to prevent installation of documentation, which is
helpful for things like RPM that have their own method of installing
documentation.

calls with new or now-built-in versions.  Make sure that all
calls to AC_DEFINE have a third argument, for possible use of
autoheader in the future.

messed up and we end up with the comments from included files in the output
"configure".

flags for Solaris.  The test itself is straight from libtool.