[lworld+fp16] RFR: 8334432: Refine Float16.fma [v2]

[Joe Darcy]

> Adding comments and test cases for Float16.fma.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Respond to review feedback.
 - Merge branch 'lworld+fp16' into JDK-8334432
 - JDK-8334432: Refine Float16.fma

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1143/files
  - new: https://git.openjdk.org/valhalla/pull/1143/files/2a321de9..ce044ce2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1143&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1143&range=00-01

  Stats: 1433 lines in 39 files changed: 648 ins; 52 del; 733 mod
  Patch: https://git.openjdk.org/valhalla/pull/1143.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1143/head:pull/1143

PR: https://git.openjdk.org/valhalla/pull/1143