Move towards build-time configuration of variables

Move towards build-time configuration of variables

We moved a lot of variable configuration into AC_CONFIG_FILES in
autoconf for the sake of convenience, but that turned out to be
problematic, as James Fournie noted in LP 960552, as the warning in
http://www.gnu.org/software/automake/manual/html_node/Scripts.html
notes: "building scripts this way has one drawback: directory variables
such as $(datadir) are not fully expanded and may refer to other
directory variables".

This was particularly a problem for variables such as @sysconfdir@ in
code that doesn't understand shell syntax - such as Cronscript.pm.

This commit moves towards build-time configuration of those variables.
We still use *.in files, but mark the built versions as dependencies in
build recipes such that we can build and test within the source
directory without having to install the files. We also gain the
advantage of teaching "make clean" to clean up the built versions of the
files.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>