scripts/feeds: print the source of packages installed

Can be helpful in diagnosing unexpected package overlaps between
feeds/core.

Signed-off-by: Karl Palsson <karlp@remake.is>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46255 3c298f89-4303-0410-b956-a3cf2f4a3e73