* update two explicit references to jdk14 to just jdk, which no longer
points at jdk8 after #89731.
* patch an explicit -XX:+UseConcMarkSweepGC to -XX:UseG1GC, as the
former now throws an error (after having been deprecated since jdk 9)
* some configure options have been removed upstream
* need a new patch to deal with gcc format warnings
11 remains, as it is an LTS release; all existing users of 11 in
nixpkgs remain on 11 for now.
openjdk/default.nix and openjdk/darwin/default.nix become the
expressions for the current version (12 now; later 13, 14, etc.).
(note: darwin/default.nix was unreferenced; the new version is derived
from darwin/11.nix.)
