[libvirt] Tiny additional RHEL patch

Small addition to the spec file, basically if on Fedora we should not activate RHEL-5 Xen specific support, but on RHEL and possibly CentOS the flag should be passed to %configure. The test is somehow reversed because it's hard to detect building on a RHEL platform from the spec file, and that should cope well with CentOS too. Now for other rpm based environment, I welcome improvements! Daniel -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel@veillard.com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/