[foreign-abi] [Rev 01] RFR: JDK-8244270: reorganize ABI-dependent layout constants (second attempt)

[Maurizio Cimadamore]

> This is the same as https://git.openjdk.java.net/panama-foreign/pull/141 but without the jextract changes. Now that we
> have reached consensus on the jextract changes, I will integrate this first, and merge the above PR later.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Add missing file

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/147/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/147/files/0865efbc..ced75942

Webrevs:
 - full: https://webrevs.openjdk.java.net/panama-foreign/147/webrev.01
 - incr: https://webrevs.openjdk.java.net/panama-foreign/147/webrev.00-01

  Stats: 75 lines in 1 file changed: 75 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/147.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/147/head:pull/147

PR: https://git.openjdk.java.net/panama-foreign/pull/147