RFR: 8259368: Zero: UseCompressedClassPointers does not depend on UseCompressedOops [v2]

[Aleksey Shipilev]

> JDK-8241825 decoupled `UseCompressedClassPointers` and `UseCompressedOops`, and introduced `COMPRESSED_CLASS_POINTERS_DEPENDS_ON_COMPRESSED_OOPS` that platforms can set to say if their generated code is ready for this decoupling.
> 
> Zero defaults to `true` for that flag, meaning the flags are still coupled. But there is not actual coupling: Zero delegates all this work to VM code, which handles everything correctly. This makes at least one test fail with Zero:
> 
> $ CONF=linux-x86_64-zero-fastdebug make exploded-test TEST=runtime/CompressedOops/CompressedClassPointers.java
> java.lang.RuntimeException: 'Narrow klass base: 0x0000000000000000' missing from stdout/stderr
> ...
> 
> Additional testing:
>  - [x] Linux x86_64 Zero `runtime/CompressedOops/` tests

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Update copyright year

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1973/files
  - new: https://git.openjdk.java.net/jdk/pull/1973/files/5e977179..6a6a6d3a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1973&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1973&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1973.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1973/head:pull/1973

PR: https://git.openjdk.java.net/jdk/pull/1973