[foreign-memaccess+abi] RFR: Add stack walk test case that doesn't verify oops [v4]

[Jorn Vernee]

> This is a followup for the earlier quickfix of: https://github.com/openjdk/panama-foreign/pull/417
> 
> This adds another test case to TestStackWalk that catches the failing code path.
> 
> This re-uses the previously added `WhiteBox::verifyFrames`, and adds a flag to turn off the verification, which triggers the problematic code path. (I've also renamed this to just `walkFrames`, since now we don't always do verification anymore.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  - update comment in frame::verify

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

Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/423/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/423/files/35676f3c..1d0f85ea

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=423&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=423&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/423.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/423/head:pull/423

PR: https://git.openjdk.java.net/panama-foreign/pull/423