[jdk21u-dev] RFR: 8317575: AArch64: C2_MacroAssembler::fast_lock uses rscratch1 for cmpxchg result [v2]

[Boris Ulasevich]

> This is a clean backport to avoid a potentially rscratch1 register clobbering in C2_MacroAssembler::fast_lock.
> 
> Testing: jtreg tier1-3 on linux-aarch64.

Boris Ulasevich has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Backport 387504c9e4b93d162dcef7c90c57c27295858d2e

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Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/941/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/941/files/0b7747c1..0403e0e0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=941&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=941&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/941.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/941/head:pull/941

PR: https://git.openjdk.org/jdk21u-dev/pull/941