RFR: 8345259: When linking from the run-time image ALL-MODULE-PATH is not accepted [v2]

[Severin Gehwolf]

> Please review this bug fix for using `jlink` when linking from the run-time image. For regular JDK builds which include the `jmods` folder, that path is automatically added as the `--module-path` when not otherwise specified on the command line. For JDK builds with JEP 493 enabled, the `jmods` folder doesn't exist and the list of module roots needs to be computed from the system modules. However, since `jdk.jlink` isn't allowed to be added to the list of output modules when linking from the run-time image, the default module path doesn't include `jdk.jlink` and modules depending on `jdk.jlink`, currently only `jdk.jpackage`. This seems a sensible default since otherwise linking using ALL-MODULE-PATH fails, while it works with a JDK build including JMODs. See the bug for details about the issue.
> 
> When an explicit module path is being added, there is no difference. All modules on that path will be added as roots. Tests have been added for the same. Thoughts?
> 
> Testing:
> - [x] GHA, `test/jdk/tools/jlink` (all pass)
> - [x] Added jlink test.

Severin Gehwolf has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Merge branch 'master' into jdk-8345259-all-module-path-fix
 - 8345259: Disallow ALL-MODULE-PATH without explicit --module-path
 - 8345573: Module dependencies not resolved from run-time image when --limit-module is being used
 - Revert "8345259: When linking from the run-time image ALL-MODULE-PATH is not accepted"
   
   This reverts commit 93c2392b0a8ca528a8aafe16e2cca888cb4df8e6.
 - Remove runtimeImage specific test
 - Merge branch 'master' into jdk-8345259-all-module-path-fix
 - 8345259: When linking from the run-time image ALL-MODULE-PATH is not accepted

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22494/files
  - new: https://git.openjdk.org/jdk/pull/22494/files/93c2392b..6b1e8711

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22494&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22494&range=00-01

  Stats: 78855 lines in 1621 files changed: 65996 ins; 8779 del; 4080 mod
  Patch: https://git.openjdk.org/jdk/pull/22494.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22494/head:pull/22494

PR: https://git.openjdk.org/jdk/pull/22494