Call madvise hints for image dex files

After opening image spaces, perform madvise hints for the
corresponding dex files.

Moved kMadviseDexFileAccesses to oat_file.cc to not have this enabled
yet.

Bug: 63178181
Test: make and flash

(cherry picked from commit 3efecdef520e80cd79f34549c4ba3a77042d0d92)

Change-Id: If91537e098b159d00354551ce6400a806549b2ca
3 files changed