Add script to update prebuilt dex

Test: testing/update_prebuilt.sh (with changes in)
Change-Id: If3cfbc011b7a3407f6d7391abdd217aac18c1448
Merged-In: If3cfbc011b7a3407f6d7391abdd217aac18c1448
(cherry picked from commit 5d3a4ed63f0a12abe048b6e61aaee209cd79361b)
2 files changed