build: fix building error when building without libvirtd

build: fix building error when building without libvirtd

When I build libvirt without libvirtd, I receive some errors:
cp: cannot stat `/home/wency/rpmbuild/BUILDROOT/libvirt-0.8.6-1.el6.x86_64/etc/libvirt/qemu/networks/default.xml': No such file or directory

My build step:
# ./autogen.sh --without-libvirtd
# make dist
# rpmbuild --nodeps --define "_sourcedir `pwd`" --define "_without_libvirtd 1" -ba libvirt.spec

The reason is we disable network when we do not build libvirt daemon in configure.ac.
After fixing this bug, I build libvirt without libvirtd, I receive other errors:
RPM build errors:
    Installed (but unpackaged) file(s) found:
   /usr/share/doc/libvirt-0.8.6/html/32favicon.png
   /usr/share/doc/libvirt-0.8.6/html/api.html
..

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>