Partial fix for launchpad bug 489294: OpenSRF seems to depend on explicit --prefix...

Partial fix for launchpad bug 489294: OpenSRF seems to depend on explicit --prefix configure option

In the process of creating Perl and Python scripts using AC_SUBST(sysconfdir),
autoconf would generate variables like '${prefix}' if no explicit --prefix
option was passed to configure - and this would cause those scripts to fail
with syntax errors.

We can work around that, and so we shall. The bigger question is whether
creating scripts with hardcoded defaults results in problems when it comes
to creating system packages; according to http://www.gnu.org/software/hello/manual/autoconf/Installation-Directory-Variables.html
one should try to defer these changes to the Makefile so that the
destination directory can be specified at make or make install time,
instead.

At least this gets us working with no explicit configure options again.
Perhaps a packaging expert can help us out of this mire :)

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@1863 9efc2488-bf62-4759-914b-345cdb29e865