[foreign-memaccess+abi] RFR: Rename and fix issues around CABI

[Per Minborg]

I suggest renaming some variables to conform to naming conventions.
This PR also contains other minor fixes.

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Commit messages:
 - Reorder modifiers
 - Rename and fix issues around CABI

Changes: https://git.openjdk.org/panama-foreign/pull/703/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=703&range=00
  Stats: 44 lines in 3 files changed: 3 ins; 1 del; 40 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/703.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/703/head:pull/703

PR: https://git.openjdk.org/panama-foreign/pull/703