Apply this change across all the shell scripts containing tests.
Additionally this defines the environment variables $abs_srcdir,
$abs_builddir, $top_srcdir, $top_builddir, $abs_top_srcdir and
$abs_top_builddir which can now be used throughout test scripts.
podcheck.pl is run as part of the tests to perform various checks on
the documentation and the tool.
Currently we check only that the documented options matches the
options that the tool implements and vice versa. This commit would
also allow us (in future) to check --help, --long-options,
--short-options, --version output.
This commit includes scripts to run the tests and various fixes to the
manual pages to ensure that the tests pass.
