RFR: 8319316: Clarify text around which layouts a linker supports [v2]

[Jorn Vernee]

> - Add linker note about packed structs.
> - Relax language a bit to avoid implying that only listed layouts are supported.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  add examples of packed structs

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16485/files
  - new: https://git.openjdk.org/jdk/pull/16485/files/b8b5d024..fea8a263

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16485&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16485&range=00-01

  Stats: 15 lines in 1 file changed: 14 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16485.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16485/head:pull/16485

PR: https://git.openjdk.org/jdk/pull/16485