RFR: 6631: Updating version to 8.0.0

[Marcus Hirt]

This patch updates the version to 8.0.0.

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Commits:
 - ffd61fd7: Updating to 8.0.0
 - 837906dc: Updating to 8.0.0

Changes: https://git.openjdk.java.net/jmc/pull/1/files
 Webrev: https://webrevs.openjdk.java.net/jmc/1/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6631
  Stats: 376 lines in 289 files changed: 0 ins; 0 del; 376 mod
  Patch: https://git.openjdk.java.net/jmc/pull/1.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/1/head:pull/1

PR: https://git.openjdk.java.net/jmc/pull/1