[foreign-abi] FYI: Move MemoryAddress::copy (ABI version)

[Maurizio Cimadamore]

This simple patch fixes references to MemoryAddress::copy from the ABI code and tests.

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Commit messages:
 - Fix bad references to MemoryAddress::copy

Changes: https://git.openjdk.java.net/panama-foreign/pull/170/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/170/webrev.00
  Stats: 6 lines in 3 files changed: 0 ins; 1 del; 5 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/170.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/170/head:pull/170

PR: https://git.openjdk.java.net/panama-foreign/pull/170