Please support zip-based OpenJDK symbol files

This bug was originally reported by Emmanuel Bourg (@ebourg) in Debian bug #956160:

openjdk-11-jre-headless installs a zip file named ct.sym that doesn't seem
to be normalized by strip-nondeterminism:

  /usr/lib/jvm/java-11-openjdk-amd64/lib/ct.sym

Would it be possible to handle it please?