RFR: 7903923: Derive C_* layouts directly from the Linker [v4]

[Nizar Benalla]

> Depending on the platform, different `C_*`  correspond to different `JAVA_*` types. We can get those values directly from the linker.
> 
> This patch can allows us to have a common class for different platforms.
> 
> Please review, and thanks in advance!

Nizar Benalla has updated the pull request incrementally with one additional commit since the last revision:

  Drop the use of JAVA_BYTE and add a small whitespace

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Changes:
  - all: https://git.openjdk.org/jextract/pull/269/files
  - new: https://git.openjdk.org/jextract/pull/269/files/461d714f..f879022f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=269&range=03
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=269&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jextract/pull/269.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/269/head:pull/269

PR: https://git.openjdk.org/jextract/pull/269