RFR: 8367532: Declare all stubgen stub entries including internal cross-stub entries

[Andrew Dinn]

This PR adds declarations for internal entries used to daisy chain memory copy stubs and ensures they are saved to generated fields when produced and accessed via those fields when consumed. This will ensure they are saved and restored correctly when stubgen blobs are included in the AOT Code Cache.

The PR also fixes a few AArch64 stubs which do not currently have their first entry at offset 0, another thing that will be needed to simplify AOT Code cache save and restore.

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Commit messages:
 - mark internal cross-stub entry as a runtime target on AArch64
 - correct aarch64 and riscv arraycopy stub cross-targets
 - correct typos in x86 code
 - ensure all cross stub calls use declared entries
 - first stub entry must be at offset 0

Changes: https://git.openjdk.org/jdk/pull/27228/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27228&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367532
  Stats: 533 lines in 8 files changed: 273 ins; 54 del; 206 mod
  Patch: https://git.openjdk.org/jdk/pull/27228.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27228/head:pull/27228

PR: https://git.openjdk.org/jdk/pull/27228