RFR: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports [v4]

[Doug Simon]

> A number of jtreg tests require a specific GC. These tests should be ignored when EnableJVMCI is true and the JVMCI compiler does not support the required GC.
> 
> This PR adds `JVMCICompiler.isGCSupported` and makes use of it in `WhiteBox.isGCSupported`.
> 
> Prior to this PR, a test requiring a GC not yet supported by a JVMCI compiler fail as follows:
> Error occurred during initialization of VM
> JVMCI Compiler does not support selected GC: epsilon gc

Doug Simon 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 remote-tracking branch 'openjdk-jdk/master' into JDK-8257020
 - implemented isGCSupported in Graal compiler
 - removed JVMCI logic from GCConfig and introduced WhiteBox.isGCSupportedByJVMCI instead
 - removed broken check_jvmci_supported_gc logic
 - removed redundant signature
 - move logic to GCConfig
 - enable a JVMCICompiler to specify which GCs it supports

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1423/files
  - new: https://git.openjdk.java.net/jdk/pull/1423/files/384287b7..6e6aef0a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1423&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1423&range=02-03

  Stats: 9695 lines in 261 files changed: 3265 ins; 1008 del; 5422 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1423.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1423/head:pull/1423

PR: https://git.openjdk.java.net/jdk/pull/1423