RFR: 8300399: EdDSA does not verify when there is no message

[Weijun Wang]

Verify should go on even if there is no message.

-------------

Commit messages:
 - chmod
 - the fix

Changes: https://git.openjdk.org/jdk/pull/12059/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12059&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300399
  Stats: 54 lines in 2 files changed: 50 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12059.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12059/head:pull/12059

PR: https://git.openjdk.org/jdk/pull/12059