[vectorIntrinsics+fp16] RFR: 8290204: FP16 initial backend implementation [v4]

[Smita Kamath]

> Initial backend implementation for enabling FP16.

Smita Kamath has updated the pull request incrementally with one additional commit since the last revision:

  Updated leaf level assembly routines as per review comment

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Changes:
  - all: https://git.openjdk.org/panama-vector/pull/204/files
  - new: https://git.openjdk.org/panama-vector/pull/204/files/6cb10daf..7677dbb2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=panama-vector&pr=204&range=03
 - incr: https://webrevs.openjdk.org/?repo=panama-vector&pr=204&range=02-03

  Stats: 110 lines in 3 files changed: 69 ins; 9 del; 32 mod
  Patch: https://git.openjdk.org/panama-vector/pull/204.diff
  Fetch: git fetch https://git.openjdk.org/panama-vector pull/204/head:pull/204

PR: https://git.openjdk.org/panama-vector/pull/204