The libexec program libvirt_iohelper is only for libvirtd. If we build rpm
without libvirtd, we will receive the following messages:

Checking for unpackaged file(s): /usr/lib/rpm/check-files /home/wency/rpmbuild/BUILDROOT/libvirt-0.9.0-1.el6.x86_64
error: Installed (but unpackaged) file(s) found:
   /usr/libexec/libvirt_iohelper