Show net upgrade size on -U/-S operations

If it is different than the raw installed size metric we already show,
compute the net upgrade size. For some sync operations, this can even be
negative if newer packages are smaller than the ones they replace
locally. Implements FS#12566.

Example:

    Targets (1): telepathy-glib-0.14.7-1

    Total Download Size:    1.07 MiB
    Total Installed Size:   15.72 MiB
    Net Upgrade Size:       -0.29 MiB

Signed-off-by: Dan McGee <dan@archlinux.org>

0 files changed, 0 insertions, 0 deletions