RFR: 8275821: Optimize random number generators developed in JDK-8248862 using Math.unsignedMultiplyHigh() [v2]

[Vamsi Parasa]

> This change optimizes random number generators using Math.unsignedMultiplyHigh()

Vamsi Parasa has updated the pull request incrementally with two additional commits since the last revision:

 - Fix year in copyright
 - micro benchmarks to test the performance

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6206/files
  - new: https://git.openjdk.java.net/jdk/pull/6206/files/c6ec6487..e46c2d92

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6206&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6206&range=00-01

  Stats: 94 lines in 1 file changed: 94 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6206.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6206/head:pull/6206

PR: https://git.openjdk.java.net/jdk/pull/6206