libjson-c: rename the libjson binary package to libjson-c, add a new libjson package with the compatibility library (to deal with the rename)

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37119 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: fix initramfs images generation after r37049

Signed-off-by: Florian Fainelli <florian@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37120 3c298f89-4303-0410-b956-a3cf2f4a3e73