Normalize alpm download callback's frontend cb arguments

When curl calls alpm's dlcb, alpm calls the frontend's cb with the
following (dlsize, totalsize) arguments:

0, -1: initialize
0, 0: no change since last call
x {x>0, x<y}, y {y>0}: data downloaded, total size known
x {x>0}, x: download finished

If total size is not known, do not call frontend cb (no change to
original behavior); alpm's callback shouldn't be called if there is a
download error.

See agregory's original spec here:
https://wiki.archlinux.org/index.php/User:Apg#download_callback

Signed-off-by: Allan McRae <allan@archlinux.org>

0 files changed, 0 insertions, 0 deletions