RFR: 8329816: Add SLEEF version 3.6.1 [v2]

[Magnus Ihse Bursie]

> [JDK-8312425](https://bugs.openjdk.org/browse/JDK-8312425) is looking to optimize vector math operations by leveraging the SLEEF library. For legal reasons the actual contribution of the SLEEF files needs to be handled separately.
> 
> This is a new attempt at solving [JDK-8329816](https://bugs.openjdk.org/browse/JDK-8329816); the original attempt is here: https://github.com/openjdk/jdk/pull/19185. This PR is based on the discussions on how to move forward that was held in that original PR.

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Update the generated sources based on the whitespace-fixed upstream source

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20781/files
  - new: https://git.openjdk.org/jdk/pull/20781/files/ccfe566e..c4c58e6c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20781&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20781&range=00-01

  Stats: 603 lines in 3 files changed: 0 ins; 0 del; 603 mod
  Patch: https://git.openjdk.org/jdk/pull/20781.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20781/head:pull/20781

PR: https://git.openjdk.org/jdk/pull/20781