RFR: 8285404: RSA signature verification should follow RFC 8017 8.2.2 Step 4

[Weijun Wang]

Compare encoded instead of decoded digest in RSA signature verification.

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Commit messages:
 - RFC 8017 8.2.2 Step 4

Changes: https://git.openjdk.java.net/jdk/pull/8365/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8365&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285404
  Stats: 30 lines in 2 files changed: 3 ins; 26 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8365.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8365/head:pull/8365

PR: https://git.openjdk.java.net/jdk/pull/8365