RFR: 8340205: Native linker allows MemoryLayout consisting of only PaddingLayout [v5]

[Per Minborg]

> This PR prevents sequence layout with padding to be used with the Linker.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Reword doce

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21041/files
  - new: https://git.openjdk.org/jdk/pull/21041/files/bba0b784..b755c61d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21041&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21041&range=03-04

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/21041.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21041/head:pull/21041

PR: https://git.openjdk.org/jdk/pull/21041