RFR: Copy of base64 micros from openjdk main for jdk8 comparisons

[Eric Caspole]

On Wed, 5 Oct 2022 09:09:58 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> Include a few recently added Base64 micros to facilitate comparisons and tracking progress from JDK 8 and onwards.

Good.

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Marked as reviewed by ecaspole (Committer).

PR: https://git.openjdk.org/jmh-jdk-microbenchmarks/pull/12