8074840: Resolve disabled warnings for libjli and libjli_static

[zzambers]

Backport, which fixes compiler errors/warnings in libjli.

Motivation:

• to fix compilation error (and some warnings) on macos-15 (clang):

...
2025-11-19T17:50:19.3284070Z /Users/runner/work/jdk8u-dev/jdk8u-dev/jdk/jdk/src/share/bin/parse_manifest.c:680:12: note: use '==' to turn this assignment into an equality comparison
2025-11-19T17:50:19.3285850Z   680 |     if (rc = find_file(fd, &entry, manifest_name) != 0) {
2025-11-19T17:50:19.3286370Z       |            ^
2025-11-19T17:50:19.3287050Z       |            ==
2025-11-19T17:50:19.3287530Z 4 warnings generated.
2025-11-19T17:50:19.3289930Z /Users/runner/work/jdk8u-dev/jdk8u-dev/jdk/jdk/src/share/bin/splashscreen_stubs.c:64:30: error: incompatible pointer to integer conversion returning 'void *' from a function with result type 'int' [-Wint-conversion]
2025-11-19T17:50:19.3291940Z    64 |     INVOKE(SplashLoadMemory, NULL)(pdata, size);
2025-11-19T17:50:19.3292900Z       |                              ^~~~
...

Differences in 8:

• excluded changes in jdk/make/lib/CoreLibraries.gmk due to differences in build system (not applicable to 8)
• excluded cast of STACK_SIZE_MINIMUM in java.c, as JDK-6762191, which adds that code, is missing in 8
• excluded modifications to readAt function in parse_manifest.c, as function was added by JDK-8073158, which is missing in 8
• copyright differences due to missing backports or backport applied out of order (some had to be updated manually)
• differences in paths

Apart from above differences most of remaining code changes applied cleanly (with updated paths).

Testing:
Tier1 in GHA: OK (Failures of TestCPUAwareness.java are unrelated)

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8074840 needs maintainer approval

Issue

• JDK-8074840: Resolve disabled warnings for libjli and libjli_static (Bug - P3)

Reviewers

• Paul Hohensee (@phohensee - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk8u-dev.git pull/733/head:pull/733
$ git checkout pull/733

Update a local copy of the PR:
$ git checkout pull/733
$ git pull https://git.openjdk.org/jdk8u-dev.git pull/733/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 733

View PR using the GUI difftool:
$ git pr show -t 733

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk8u-dev/pull/733.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back zzambers! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (a6b2a35f)

[openjdk]

⚠️ @zzambers This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.