RFR: 8329331: Intrinsify Unsafe::setMemory [v10]

[Scott Gibbons]

> This code makes an intrinsic stub for `Unsafe::setMemory` for x86_64.  See [this PR](https://github.com/openjdk/jdk/pull/16760) for discussion around this change.
> 
> Overall, making this an intrinsic improves overall performance of `Unsafe::setMemory` by up to 4x for all buffer sizes.
> 
> Tested with tier-1 (and full CI).  I've added a table of the before and after numbers for the JMH I ran (`MemorySegmentZeroUnsafe`).
> 
> [setMemoryBM.txt](https://github.com/openjdk/jdk/files/14808974/setMemoryBM.txt)

Scott Gibbons has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 19 commits:

 - Merge master
 - Set memory test (#16)
   
   Add framework for other platforms.  Moved fill_to_memory_atomic back to the .cpp from the .hpp in order to get 32-bit fixed.
 - Address review comments (#15)
   
   * Address review comments
 - Add movq to locate_operand
 - Oops
 - Fixed generate_fill when count > 0x80000000
 - Fix Windows
 - Addressing review comments.
 - Remove dead code
 - Use non-sse fill (old left in)
 - ... and 9 more: https://git.openjdk.org/jdk/compare/31ee5108...41ffcc32

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

Changes: https://git.openjdk.org/jdk/pull/18555/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18555&range=09
  Stats: 734 lines in 38 files changed: 680 ins; 5 del; 49 mod
  Patch: https://git.openjdk.org/jdk/pull/18555.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18555/head:pull/18555

PR: https://git.openjdk.org/jdk/pull/18555