--checkapi=equal checks the equality of two dumps

Switched from diff-based test, which often breaks for trivial changes.
For example, changing '/* @hide */' to '/** @hide */' shouldn't break
the equality of two dumps.

Similarly, adding license/copyright headers to dumped .aidl files
shouldn't break the equality.

Bug: 172476424
Test: m (triggers checks)
Change-Id: Iea2d3b9f8597977ab276828e943dd6e84debc8ce
8 files changed