source: Use lrPackageTarget v2 API to prep for improved callbacks
source: Use lrPackageTarget v2 API to prep for improved callbacks

Using this API will allow us to use the mirrorfailure callback, which
in turn will allow better error messages.

Side note: This reveals that we're downloading packages serially
rather than handing them as a bunch to librepo, which would allow much
more parallelism.

rpm-software-management/libhif,hughsie/libhif,edynox/libdnf,rpm-software-management/libhif,edynox/libdnf,rpm-software-management/libdnf,hughsie/libhif,cgwalters/libhif,rpm-software-management/libdnf,rpm-software-management/libdnf,Conan-Kudo/libhif,Conan-Kudo/libhif,juhp/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif,hughsie/libhif,edynox/libdnf,hughsie/libhif,juhp/libhif,rpm-software-management/libhif,edynox/libdnf,cgwalters/libhif,rpm-software-management/libhif,rpm-software-management/libdnf,cgwalters/libhif,cgwalters/libhif