Fenix's classes5.dex files are not reproducible

When building .apk files with the https://gitweb.torproject.org/user/gk/tor-browser-build.git/commit/?h=bug_33927_v2&id=a9eca52f63d049f0cb1a03c14971c8743d79a2b1 it turns out the classes5.dex files are not getting built deterministically for all 4 architectures. Looking at the diff for armv7 (attached) there is at least a timestamp issues we need to fix, but maybe more.