Improved 4-byte alignment fixes.

This improves tests for 4-byte alignment and does some small code
cleanup to make the reason why we need 6 bytes of header for 4 byte
alignment more clear.

Bug: http://b/67995001
Test: Included
Change-Id: I12148519bb360c3b71e97d880f31f111c4feb4aa
3 files changed
tree: d5540a3e9aee19e4f2020cfa58e3e4d4c9f6833a
  1. src/
  2. apkzlib.iml
  3. BUILD
  4. build.gradle