Bug 1051191 - Build recovery updater for FOTA package r=mwu

By default, we are using a prebuilt updater binary that dates back to
ICE era. This is not good, because:
 - we cannot extend the recovery updater tool if we need
 - new versions of the aosp framework have introduced changes to some of
   the edify functions, which means we cannot use then with the prebuilt
 - it may just fail (flame/kk getprop() as described in bug 1067005,
   comment 18).