Add dex file writer to dexlayout tool.

All sections are being written out properly.
There is one small difference:
  - unindexed string data is not written out

Bug: 29921113
Test: mm test-art-host-gtest-dexlayout_test
Change-Id: I3872327526a350f33f0f851516a389622c1a54ae
8 files changed