Fixes new javac failures caused by #1542 when Attributes.loadableDescriptors is now preview. (It should probably be a reflective preview API; that will be addressed in #1439)
------------- Commit messages: - LoadableDescriptorsAttrTest2 uses preview API Attributes.loadableDescriptors Changes: https://git.openjdk.org/valhalla/pull/1543/files Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1543&range=00 Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod Patch: https://git.openjdk.org/valhalla/pull/1543.diff Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1543/head:pull/1543 PR: https://git.openjdk.org/valhalla/pull/1543
