RFR: JDK-8289551: Conversions between bit representations of half precision values and floats [v3]

[Joe Darcy]

> Initial implementation.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Preserve NaN sign bit.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9422/files
  - new: https://git.openjdk.org/jdk/pull/9422/files/b09fdfc3..420a9f3f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9422&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9422&range=01-02

  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9422.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9422/head:pull/9422

PR: https://git.openjdk.org/jdk/pull/9422