RFR: 8259074: regex benchmarks and tests

[Martin Buchholz]

8259074: regex benchmarks and tests

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Commit messages:
 - more benchmarks
 - JDK-8259074

Changes: https://git.openjdk.java.net/jdk/pull/1940/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1940&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259074
  Stats: 444 lines in 5 files changed: 442 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1940.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1940/head:pull/1940

PR: https://git.openjdk.java.net/jdk/pull/1940