[libvirt] [PATCH] Don't log qemu monitor output from blockStats

The attached patch changes the qemu driver blockStats command to not log qemu monitor output. virt-manager offers an option to continually poll VM disk stats, and if the app is left running for a while with many VMs, this can make the logs huge, for little benefit (a user reported 100 MB with virt-manager left running overnight). The output from the command is still printed with a DEBUG call, so the info isn't completely lost. Thanks, Cole