Add a fetch callback to allow front-end download support

This allows a frontend to define its own download algorithm so that the
libfetch dependency can be omitted without using an external process.
The callback will be used when if it is defined, otherwise the old
behavior applies.

Signed-off-by: Sebastian Nowicki <sebnow@gmail.com>
[Dan: minor cleanups]
Signed-off-by: Dan McGee <dan@archlinux.org>

0 files changed, 0 insertions, 0 deletions