[foreign-memaccess+abi] RFR: Cleanup class issues

[Per-Åke Minborg]

This PR resolves some typos and structural issues.

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Commit messages:
 - Cleanup class issues

Changes: https://git.openjdk.org/panama-foreign/pull/696/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=696&range=00
  Stats: 39 lines in 11 files changed: 11 ins; 4 del; 24 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/696.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/696/head:pull/696

PR: https://git.openjdk.org/panama-foreign/pull/696