libqtest: Clean up unused QTestState member sigact_old Unused since commit d766825. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <1443689999-12182-6-git-send-email-armbru@redhat.com> Reviewed-by: Thomas Huth <thuth@redhat.com>