libvirt-guests invokes functions in gettext.sh, so we need to
require gettext package in spec file.

Demo with the fix:
% rpm -q gettext
package gettext is not installed

% rpm -ivh libvirt-client-0.8.8-1.fc14.x86_64.rpm
error: Failed dependencies:
	gettext is needed by libvirt-client-0.8.8-1.fc14.x86_64

* libvirt.spec.in