RFR: Migrate j.l.Characters JMH from JDK for more easy use with 8

[Eric Caspole]

This JMH was added with JBS 8213754.

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

Commit messages:
 - Migrate j.l.Characters JMH from JDK for more easy use with 8

Changes: https://git.openjdk.org/jmh-jdk-microbenchmarks/pull/15/files
 Webrev: https://webrevs.openjdk.org/?repo=jmh-jdk-microbenchmarks&pr=15&range=00
  Stats: 70 lines in 1 file changed: 70 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jmh-jdk-microbenchmarks/pull/15.diff
  Fetch: git fetch https://git.openjdk.org/jmh-jdk-microbenchmarks pull/15/head:pull/15

PR: https://git.openjdk.org/jmh-jdk-microbenchmarks/pull/15