Roll our own version of zipalign so that we can break the dependency
on the build tools zipalign. This breaks the transitive dependency
on androidfw so that building bionic unit tests in brillo works again.
Also modify the DlExtTest.ExtInfoUseFdWithOffset test so it dynamically
gets the offset of the shared library inside of the zip instead of
hard-coding the value.
Bug: 25446938
Change-Id: Idfb5d3089960a94eefa2c76e03da1ad2f4d7fb2f