Skip gpg-error-config-test.sh for specific incompatible pkg-config.

* src/gpg-error-config-test.sh.in: Skip the test with pkgconf 1.8.0.

Possibly, we need to skip with 1.9.0, 1.9.1, 1.9.2, and 1.9.3, too.
pkgconf 1.8.1 (on Debian) works well.

• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>