[jdk17u-dev] RFR: 8272315: Improve assert_different_registers

[Martin Doerr]

Clean backport of [JDK-8272315](https://bugs.openjdk.org/browse/JDK-8272315). It's only an enhancement, but it is required for other changes. E.g. the "Represent Registers as values" changes which were done for GCC 11 support like [JDK-8297445](https://bugs.openjdk.org/browse/JDK-8297445) don't build without it: `no known conversion for argument 1 from 'Register' to 'AbstractRegister' {aka 'AbstractRegisterImpl*'}`

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Commit messages:
 - Backport 93cab7d07d56fef6973ce8ac2e8232e8f3b185dd

Changes: https://git.openjdk.org/jdk17u-dev/pull/2448/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2448&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8272315
  Stats: 257 lines in 1 file changed: 0 ins; 246 del; 11 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2448.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2448/head:pull/2448

PR: https://git.openjdk.org/jdk17u-dev/pull/2448