Dexlayout cleanup and refactoring.

Created option to output to a mem map in preparation of hooking
dexlayout into dex2oat.

Test: mm test-art-host-gtest-dexlayout_test
Bug: 29921113
Change-Id: Id42ef15cb8f83cc8d05b025b7647a4338e9b96b0
11 files changed