[automerger skipped] Add boot.img substitution to the build_mixed script. am: aabbd91ab5
am: d82dc77cda -s ours
am skip reason: change_id I2877e79522b5836e876c87f38221ca6890c41ce6 with SHA1 22da1576b1 is in history

Change-Id: I09bbff76d6fa1215e15febc3760ddd2852ae21ae