[foreign-memaccess] RFR: JDK-8242253: Clarify bulk of addresses backed by same storage

[Paul Sandoz]

Here is a small tweak to the specification of `MemoryAddress.copy` when source and target address ranges do not
overlap, but there are overlapping regions of the same backing storage.

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Commit messages:
 - JDK-8242253: Clarify bulk of addresses backed by same storage

Changes: https://git.openjdk.java.net/panama-foreign/pull/101/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/101/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-JDK-8242253
  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/101.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/101/head:pull/101

PR: https://git.openjdk.java.net/panama-foreign/pull/101