RFR: 8267112: JVMCI compiler modules should be kept upgradable

[Mandy Chung]

On Thu, 13 May 2021 16:37:38 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> [JDK-8264806](https://bugs.openjdk.java.net/browse/JDK-8264806) changes removed sources and also removed JVMCI compiler from list of upgradable modules. JVMCI compiler modules should be upgradable in JDK to work with GraalVM. 
> 
> Make these modules upgradable again and empty by leaving only reference to JVMCI (jdk.internal.vm.ci) module. It does not restore sources - only `module-info.java` files are kept.
> 
> Note, we continue discussion about [JDK-8265091](https://bugs.openjdk.java.net/browse/JDK-8265091): "Use Module API to export JVMCI packages at runtime" to see if we can remove these `module-info.java` files.
> 
> Changes were proposed by @dougxc after testing [JDK-8264806](https://bugs.openjdk.java.net/browse/JDK-8264806) changes with GraalVM.
> I restored related code in some tests for them to pass.
> 
> Testing: full tier1-tier3.

Marked as reviewed by mchung (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/4014