RFR: 8311302: Allow for jlinking a custom runtime without packaged modules being present [v9]

[Severin Gehwolf]

> Please review this patch which adds a "jmodless" jlink mode to the JDK. Fundamentally this patch adds an option to use `jlink` even though your JDK install might not come with the packaged modules (directory `jmods`). This is particularly useful to further reduce the size of a jlinked runtime. After the removal of the concept of a JRE, a common distribution mechanism is still the full JDK with all modules and packaged modules. However, packaged modules can incur an additional size tax. For example in a container scenario it could be useful to have a base JDK container including all modules, but without also delivering the packaged modules. This comes at a size advantage of `~25%`. Such a base JDK container could then be used to `jlink` application specific runtimes, further reducing the size of the application runtime image (App + JDK runtime; as a single image *or* separate bundles, depending on the app being modularized).
> 
> The basic design of this approach is to add a jlink plugin for tracking non-class and non-resource files of a JDK install. I.e. files which aren't present in the jimage (`lib/modules`). This enables producing a `JmodLessArchive` class which has all the info of what constitutes the final jlinked runtime.
> 
> Basic usage example:
> 
> $ diff -u <(./bin/java --list-modules --limit-modules java.se) <(../linux-x86_64-server-release/images/jdk/bin/java --list-modules --limit-modules java.se)
> $ diff -u <(./bin/java --list-modules --limit-modules java.se) <(../linux-x86_64-server-release/images/jdk/bin/java --list-modules --limit-modules jdk.jlink)
> $ ls ../linux-x86_64-server-release/images/jdk/jmods
> java.base.jmod            java.net.http.jmod       java.sql.rowset.jmod      jdk.crypto.ec.jmod         jdk.internal.opt.jmod                     jdk.jdi.jmod         jdk.management.agent.jmod  jdk.security.auth.jmod
> java.compiler.jmod        java.prefs.jmod          java.transaction.xa.jmod  jdk.dynalink.jmod          jdk.internal.vm.ci.jmod                   jdk.jdwp.agent.jmod  jdk.management.jfr.jmod    jdk.security.jgss.jmod
> java.datatransfer.jmod    java.rmi.jmod            java.xml.crypto.jmod      jdk.editpad.jmod           jdk.internal.vm.compiler.jmod             jdk.jfr.jmod         jdk.management.jmod        jdk.unsupported.desktop.jmod
> java.desktop.jmod         java.scripting.jmod      java.xml.jmod             jdk.hotspot.agent.jmod     jdk.internal.vm.compiler.management.jmod  jdk.jlink.jmod       jdk.naming.dns.jmod        jdk.unsupported...

Severin Gehwolf has updated the pull request incrementally with 10 additional commits since the last revision:

 - Typo fix.
 - Add a proper test for generate-jli-classes in run-image based link mode
 - Fix corner case of system modules not consistently being enabled
 - Remove work-arounds for AddOptions and SaveJlinkArgfiles Plugins
   
   We now filter the resources in the run-time-image link mode. Similar
   to what we do for system-modules and generate-jli-classes plugins.
 - Fix SystemModulesPlugin in run-time link mode
 - Fix GenerateJLIClassesPlugin in run-time link mode
 - Update some comments
 - Mark --unlock-run-image as a hidden option
 - Fix some comments in GenerateJLIClassesPlugin
 - Use internal package name for run-image resources
   
   They are now in the jdk.jlink module and have prefix:
   /jdk.jlink/jdk/tools/jlink/internal/runlink_
   
   For example for java.base, the resource file is:
   /jdk.jlink/jdk/tools/jlink/internal/runlink_java.base_resources

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14787/files
  - new: https://git.openjdk.org/jdk/pull/14787/files/ac01194c..3539c6a5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14787&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14787&range=07-08

  Stats: 490 lines in 13 files changed: 327 ins; 111 del; 52 mod
  Patch: https://git.openjdk.org/jdk/pull/14787.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14787/head:pull/14787

PR: https://git.openjdk.org/jdk/pull/14787