docs: removed outdated reference to virt-mem

The virt-mem program is no longer shipped, but was still being
referenced at the bottom of the virsh and libvirtd man pages.

This patch removes it from those man pages, addressing
BZ# 639603:

  https://bugzilla.redhat.com/show_bug.cgi?id=639603

daemon/libvirtd.pod.in

@@ -163,6 +163,6 @@ PURPOSE
 =head1 SEE ALSO
 
 L<virsh(1)>, L<virt-install(1)>, L<virt-xml-validate(1)>, L<virt-top(1)>,
-L<virt-mem(1)>, L<virt-df(1)>, L<http://www.libvirt.org/>
+L<virt-df(1)>, L<http://www.libvirt.org/>
 
 =cut

tools/virsh.pod

@@ -1259,6 +1259,7 @@ PURPOSE
 
 =head1 SEE ALSO
 
-L<virt-install(1)>, L<virt-xml-validate(1)>, L<virt-top(1)>, L<virt-mem(1)>, L<virt-df(1)>, L<http://www.libvirt.org/>
+L<virt-install(1)>, L<virt-xml-validate(1)>, L<virt-top(1)>, L<virt-df(1)>,
+L<http://www.libvirt.org/>
 
 =cut