RFR: 8188044: We need Math.unsignedMultiplyHigh

[Brian Burkhalter]

Please consider this proposal to add a method `unsignedMultiplyHigh(long,long)` to each of `java.lang.Math` and `java.lang.StrictMath`.

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

Commit messages:
 - 8188044: We need Math.unsignedMultiplyHigh

Changes: https://git.openjdk.java.net/jdk/pull/4644/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4644&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8188044
  Stats: 72 lines in 3 files changed: 62 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4644.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4644/head:pull/4644

PR: https://git.openjdk.java.net/jdk/pull/4644