RFR: 8344912: Sharpen the return type of various internal methods in jdk.internal.foreign [v2]

[Quan Anh Mai]

> Hi,
> 
> This patch sharpens the return types of various internal methods. This helps the compiler to have better information when the corresponding methods are not inlined.
> 
> Please take a look and leave your reviews, thanks a lot.

Quan Anh Mai has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  sharpen the return types of various FFM internal methods

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22344/files
  - new: https://git.openjdk.org/jdk/pull/22344/files/d81888fc..cf69f90f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22344&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22344&range=00-01

  Stats: 98 lines in 10 files changed: 5 ins; 0 del; 93 mod
  Patch: https://git.openjdk.org/jdk/pull/22344.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22344/head:pull/22344

PR: https://git.openjdk.org/jdk/pull/22344