Keep oat file unique pointers until they are no longer used.

Before, the unique pointer would be deleted before we were finished
using the dex file we opened from the oat file.

Bug: 28359191

(cherry-picked from commit a6d46161aea07ebd1cbd6ab78b2b323f940e9c1e)

Change-Id: I737d17536967af48d8748bde2b266a82410830b7
1 file changed