Use symlinks for upstream changelog

This safes 1.9M per package

debian/libvirt-bin.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-bin/changelog.gz

debian/libvirt-clients.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-clients/changelog.gz

debian/libvirt-daemon-system.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-daemon-system/changelog.gz

debian/libvirt-daemon.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-daemon/changelog.gz
+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-daemon/changelog.gz

debian/libvirt-dev.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-dev/changelog.gz

debian/libvirt-doc.links

 usr/share/doc/libvirt-doc/devhelp/	/usr/share/gtk-doc/html/libvirt
+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-doc/changelog.gz

debian/libvirt-sanlock.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt-sanlock/changelog.gz

debian/libvirt0-dbg.links

+usr/share/doc/libvirt0/changelog.gz usr/share/doc/libvirt0-dbg/changelog.gz

debian/rules

@@ -200,3 +200,7 @@ override_dh_auto_clean:
 	rm -f $(CURDIR)/debian/libvirt-daemon-system.*.logrotate
 	rm -f $(CURDIR)/debian/*.service
 	rm -rf $(DEB_BUILDDIR)
+
+override_dh_installchangelogs:
+	dh_installchangelogs -plibvirt0
+	dh_installchangelogs -Nlibvirt0 -XChangeLog