qemuBuildSoundCommandLine: Generate codecs via JSON
qemuBuildSoundCommandLine: Generate codecs via JSON

The codec devices have the following properties we control:
  cad=<uint32>           -  (default: 4294967295)
  audiodev=<str>         - ID of an audiodev to use as a backend

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

libvirt/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,crobinso/libvirt,libvirt/libvirt,jfehlig/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,zippy2/libvirt,zippy2/libvirt,olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt