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
