[foreign-memaccess] RFR: 8253305: The threshold for the shared segment handshake stackwalk is too low

[Maurizio Cimadamore]

This patch slightly increases the threshold for the stack walk during the shared segment handshake.
We found instances (MemorySegment::copy) where more than 5 frames were inserted beteween top of stack and first scoped
frame.

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Commit messages:
 - Raise the threshold for the handshake stackwalk

Changes: https://git.openjdk.java.net/panama-foreign/pull/337/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=337&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253305
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/337.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/337/head:pull/337

PR: https://git.openjdk.java.net/panama-foreign/pull/337