Upgrade to latest Gnulib version and fix resulting FreeBSD build failures.

Upgrading the Gnulib version exposed a couple of failures to #include
<config.h> at the very top of a source file via build failures on
FreeBSD 7.2-RELEASE, fixed by this commit.

This probably also fixes a similar OpenBSD issue reported by Jason Stover
at http://lists.gnu.org/archive/html/pspp-dev/2009-09/msg00095.html