Update to jdk-16.0.0.0+36
    
    Update tarball generation script to use git following OpenJDK's move to github
    Update tarball generation script to use PR3823 which handles JDK-8235710 changes
    Use upstream default for version-pre rather than setting it to "ea" or ""
    Drop libsunec.so which is no longer generated, thanks to JDK-8235710
    Drop unnecessary compiler flags, dating back to work on GCC 6 & 10
    Adapt RH1750419 alt-java patch to still apply after some variable re-naming in the makefiles
    Update filever to remove any trailing zeros, as in the OpenJDK build, and use for source filename
    Use system harfbuzz now this is supported.
    Pass SOURCE_DATE_EPOCH to build for reproducible builds