Add feed update option '-r' to perform "git pull --rebase" so that
possible local commits are rebased on top of the new commits pulled
from origin. That enables git pull while there are local
development commits.
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
Link: https://github.com/openwrt/openwrt/pull/15377
Signed-off-by: Robert Marko <robimarko@gmail.com>