RFR: 8300255: Introduce interface for GC oop verification in the assembler [v2]

[Erik Österlund]

> In the assembly code, there is some generic oop verification code. Said verification may or may not fit a particular GC. In particular, it has not worked well for ZGC for a while, and there is an if (UseZGC). This enhancement aims at generalizing this code, such that a collector can have its own oop verification policy.

Erik Österlund has updated the pull request incrementally with one additional commit since the last revision:

  RISC-V build fix

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12443/files
  - new: https://git.openjdk.org/jdk/pull/12443/files/0779af3e..c5617992

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12443&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12443&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12443.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12443/head:pull/12443

PR: https://git.openjdk.org/jdk/pull/12443