Add new function to manage adding the controller -device options to the
command line removing that task from the mainline qemuBuildCommandLine.

Also adjust to using const virDomainDef instead of virDomainDefPtr.
This causes collateral damage in order to modify called APIs to use
the const virDomainDef instead as well.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>