init: require e2fsdroid and mke2fs when building init

init calls fs_mgr to format ext4 partitions. This requires
e2fsdroid and mke2fs in /system/bin/

Bug: 35219933
Change-Id: Ia32fe438cd9b9332f8e18e0cbe7f61bd050adcb1
(cherry picked from commit 041f8495)