RFR: 7903984: Inline upcallHandle method to reduce shared code across multiple generations [v4]

[Nizar Benalla]

> Please review this patch to inline the upcallHandle method, reducing the amount of shared items across multiple jextract generations.
> 
> Edit: all tests pass in CI, GitHub failure is unrelated 
> 
> TIA

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

  make utility classes final with a private constructor

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

Changes:
  - all: https://git.openjdk.org/jextract/pull/279/files
  - new: https://git.openjdk.org/jextract/pull/279/files/fc8c1471..3f2d95e7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=279&range=03
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=279&range=02-03

  Stats: 24 lines in 3 files changed: 18 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jextract/pull/279.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/279/head:pull/279

PR: https://git.openjdk.org/jextract/pull/279