RFR: 8369190: JavaFrameAnchor on AArch64 appears to be missing barriers [v2]

[Justin King]

> Add store barrier at the appropriate place in `JavaFrameAnchor::copy`. Move `sp` store to be last in `MacroAssembler::set_last_Java_frame`. Add `dmb ISHST` to `MacroAssembler::set_last_Java_frame` and `MacroAssembler::reset_last_Java_frame`.

Justin King has updated the pull request incrementally with one additional commit since the last revision:

  Rename ACGT -> AGCT
  
  Signed-off-by: Justin King <jcking at google.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27645/files
  - new: https://git.openjdk.org/jdk/pull/27645/files/a0058eb4..a1414494

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27645&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27645&range=00-01

  Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/27645.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27645/head:pull/27645

PR: https://git.openjdk.org/jdk/pull/27645