[libvirt] [PATCH 2/3]: Log argv passed to virExec and virRun

The attached patch logs the the argv's passed to the virExec and virRun functions. There's a bit of trickery here: since virRun is just a wrapper for virExec, we don't want the argv string to be logged twice. I addressed this by renaming virExec to __virExec, and keeping the original function name to simply debug the argv and then hand off control. This means anytime virExec is explictly called, the argv will be logged, but if functions wish to by pass that they can just call __virExec (which is what virRun does.) Please let me know if there are any problems with that approach. Thanks, Cole