RFR: 8360936: Test compiler/onSpinWait/TestOnSpinWaitAArch64.java fails after JDK-8359435 [v6]

[Evgeny Astigeevich]

> Test compiler/onSpinWait/TestOnSpinWaitAArch64.java needs debug info to identify a position of spin wait instructions in generated code. The test switched to use `XX:CompileCommand=print` instead of `XX:+PrintAssembly` to have assembly only for a tested Java method. In release builds  `XX:+PrintAssembly` prints out debug info but `XX:CompileCommand=print` does not.
> 
> This PR reimplements the test to parse instructions and to check them. The test does not rely on debug info anymore.
> 
> Tested on Linux and MacOS with and without hsdis:
> - Fastdebug: test passed
> - Slowdebug: test passed.
> - Release: test passed.

Evgeny Astigeevich has updated the pull request incrementally with one additional commit since the last revision:

  Update spin_wait block comment

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26072/files
  - new: https://git.openjdk.org/jdk/pull/26072/files/e3163c9f..6d60fb42

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26072&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26072&range=04-05

  Stats: 11 lines in 2 files changed: 5 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/26072.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26072/head:pull/26072

PR: https://git.openjdk.org/jdk/pull/26072