RFR: 7903632: struct accessor info is not derived from toplevel layout decl

Tue Jan 16 16:18:56 UTC 2024

This PR dials back the code generation updates a little when it comes to struct getter/setter, so that both their layouts and offsets is now derived from the toplevel struct layout - using layout paths, as before.

This allows clients to e.g. tweak layouts in a single place (the topelevel struct layout declaration) to adjust things such as endianness.

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Commit messages:
 - Initial push

Changes: https://git.openjdk.org/jextract/pull/181/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=181&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903632
  Stats: 35 lines in 2 files changed: 28 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jextract/pull/181.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/181/head:pull/181

PR: https://git.openjdk.org/jextract/pull/181