include: fix detection of installed feeds

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42003 3c298f89-4303-0410-b956-a3cf2f4a3e73
build: add new option to add disabled feeds commented out to opkg.conf

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42004 3c298f89-4303-0410-b956-a3cf2f4a3e73