RFR: 8315131: Clarify VarHandle set/get access on 32-bit platforms [v3]

[Chen Liang]

> On 32 bit platforms, when an access to long/double is aligned, it is supported but not atomic. The original wording in `MethodHandles::byteBufferViewVarHandle` sounds as if it is not supported at all. We can fix that by borrowing the improved specification from `MemoryLayout::varHandle`.
> 
> Note: This doc is copied from https://github.com/openjdk/jdk/blob/ee0d309bbd33302d8c6f35155e975db77aaea785/src/java.base/share/classes/java/lang/foreign/MemoryLayout.java#L279-L282 with slight adjustments. See the rendering at https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/lang/foreign/MemoryLayout.html#access-mode-restrictions

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  "may be non-atomic"

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26258/files
  - new: https://git.openjdk.org/jdk/pull/26258/files/1550fcc0..7563e6b7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26258&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26258&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26258.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26258/head:pull/26258

PR: https://git.openjdk.org/jdk/pull/26258