[jdk21u-dev] RFR: 8323122: AArch64: Increase itable stub size estimate

[Dmitry Chuyko]

This is a tiny safety follow-up to JDK-8307352 (AARCH64: Improve itable_stub). Original change applies cleanly.

Testing: jtreg tier1,2 on linux-aarch64.

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Commit messages:
 - Backport 36f4b34f1953af736706ec67192204727808bc6c

Changes: https://git.openjdk.org/jdk21u-dev/pull/711/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=711&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323122
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/711.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/711/head:pull/711

PR: https://git.openjdk.org/jdk21u-dev/pull/711