RFR: JDK-8302800: Augment NaN handling tests of FDLIBM methods [v2]

[Joe Darcy]

> Augment NaN-handling tests to include exotic NaN bit patterns. Assuming this changeset goes back first, I'll update https://github.com/openjdk/jdk/pull/12608 to follow the same convention afterward.

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

  Respond to review feedback.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12644/files
  - new: https://git.openjdk.org/jdk/pull/12644/files/b4f2a1dd..e2b8486d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12644&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12644&range=00-01

  Stats: 4 lines in 1 file changed: 2 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12644.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12644/head:pull/12644

PR: https://git.openjdk.org/jdk/pull/12644