TEMPORARY: Remove supersu backup script

Switched to superuser now so lets make sure supersu is completely gone.

Change-Id: Ice4bba005cf4bfc7d76b187f3622eeb712b84fde
Signed-off-by: Evan Anderson <evan@thelinuxman.us>
Merge branch 'kitkat' of github.com:AOSPA/android_build into kitkat