RFR: Workaround CacheDataStore use with source launcher

[Aleksey Shipilev]

I was trying to test the simplest workload that involves javac, and that is source launcher. When I attempt to use source launcher with `-XX:CacheDataStore`, it fails with:


$ rm -f app.cds*; build/linux-x86_64-server-release/images/jdk/bin/java -XX:CacheDataStore=app.cds -Xmx256m -Xms256m -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC HelloStream.java
[0.001s][warning][cds] optimized module handling/full module graph: disabled due to incompatible property: jdk.module.addmods=ALL-DEFAULT
Error occurred during initialization of VM
CacheDataStore cannot be created because AOTClassLinking is enabled but full module graph is disabled


Source launcher adds `--add-modules=ALL-DEFAULT`:


$ man java
...
       In source-file mode, execution proceeds as follows:

...
       • The compiled classes are executed in  the  context  of  an  unnamed  module,  as  though  --add-mod‐
         ules=ALL-DEFAULT  is  in  effect.  This is in addition to any other --add-module options that may be
         have been specified on the command line.


I think we can work that around specifically for Leyden, and also leave a TODO breadcrumb in the code that we need to figure this out on CDS side. This PR does that workaround. With it, source launcher works with simple examples:


$ build/linux-x86_64-server-release/images/jdk/bin/java -XX:CacheDataStore=app.cds -Xmx256m -Xms256m -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC  HelloStream.java
Warning: CacheDataStore cannot be used with default source launcher environment, disabling --add-modules=ALL-DEFAULT
hello, world

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

Commit messages:
 - Warning message
 - Workaround

Changes: https://git.openjdk.org/leyden/pull/15/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=15&range=00
  Stats: 14 lines in 2 files changed: 13 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/leyden/pull/15.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/15/head:pull/15

PR: https://git.openjdk.org/leyden/pull/15